Well of course, I have a boil on my face. I'm flying to Ireland in a private jet with Brian McFadden and Max Clifford to some gala black-tie launch whatever, and so, yes, I wake up with something scabrous and vaguely pustulant attached to my cheek. This so perfectly sums up the story I'm preparing to write, namely Pleb Travel versus Celeb Travel: Compare and Contrast, that I already know how it's going to pan out, ie like life: intrinsically unfair and really, if you come to think about it, a bit annoying.

I can't help feeling a puppyish sense of excitement, though. True, I have a boil, and en route to the airport, Suki, the photographer, discovers that her sole has detached itself from the rest of her boot, and we're handicapped cab-hailing-wise what with having to shield our faces/feet but still, we're going to meet Brian! And Max!

Being new to this type of thing, we turn up at Farnborough - a private airport in Hampshire dedicated to serving private jets - with a good hour to spare. This is so clearly the mistake of a pair of rank amateurs that the staff tactfully ignore us. Although, in fact, it's not so much an 'airport'; more a 'Portakabin'. Yes, there are leather sofas, and spiky orange corporate flowers and complimentary packets of Walker's Sensations crisps, but at the end of the day, it looks not unlike Barry's old mini-cab office in EastEnders. The fact that the other passengers all look vaguely Barryesque, ie, fat, badly dressed and faintly shifty, only adds to the effect.

I find a copy of OK! nestling behind Yachting World and there, on the cover, is Brian's ex, Kerry, extolling her 'Amazing Bikini Diet!'. I skim the article but there's the usual guff about vegetables and oily fish rather than the more obvious: get dumped by your husband, break down, check into the Priory, see him snogging his new ex-Neighbours girlfriend, Delta Goodrem, in all the tabloids, and, voila, you're two stone lighter. I shove it hastily into my bag though, because I spot Brian lurking outside.

He's easy enough to spot, dressed as he is in the international uniform of ex-boy-band stars everywhere: weathered denims with a cheeky hint of grey Calvins showing above his low-slung waistline, a manly jaw covered with a fine, bristly stubble, an iPod hanging casually from his pocket, an up-to-the-minute Nokia welded to the side of his face, and a head topped with the kind of artfully styled mop-top hair that my mother would describe as 'lank'.

'Hiyah,' he says when he finally strolls in and then immediately starts fiddling with his phone.

This is my first taste of travelling OK!-style and already I'm starting to clock a few, subtle differences. Suki and I, naively, I now realise, had attempted to 'check-in'. One does not 'check-in' as a celeb, it transpires. One lounges insouciantly across a leather sofa and looks impatient. Brian has more than got the hang of this. Accompanying him is Mark, his PA, and I start to suspect he might hold the real key to travelling celeb-style. 'Brian?' he says. 'Do you want a drink? Some Walker's Sensation crisps?' I'm just wondering when he's going to ask him if he needs to have a wee when I notice that Brian doesn't even have hand luggage. But then, who needs it when you have Mark?

Brian seems mildly oblivious to his good fortune in this. But then he seems mildly oblivious to many things, the most obvious of which is that he is officially here, we're all officially here, to promote the airline Euromanx's new route from London-City to Galway. In this, he's almost endearingly off-message.

'Have you ever been to Galway?' Mark asks Suki.

'No.'

'Lucky you,' says Brian looking up briefly from his Nokia.

'Why's that?' I ask.

'Ah, God. I mean, it's a dump.'

I feel a bit bad reporting this, not least towards the many fine and lovely inhabitants of Galway whom we'll both meet later that night. But hold on, I'm a journalist! And, yes, Suki and I may not be the 3am Girls what with our boil/boot problems, but still! I have a notebook, Suki a camera. It's not as if we've dressed in flowing Arabian robes and dark glasses.

'So, how did you get dragged into this?' I ask.

'Feck knows,' he says. 'Max told me to be here at three. So I'm here. I've no idea what's going on.'

I wonder if I ought to tell him. I, at least, have the advantage of having read the press release. Euromanx, an airline based on the Isle of Man, is expanding its network. But then airlines expand routes the whole time without feeling the need to chuck in a celeb and throw a black tie-bash. The difference is that Euromanx has just been bought by an Australian pilot called Warren Seymour who's also on the board of Club 328, a private-jet charter operation. And the PR for both Euromanx and Club 328 is handled by Max Clifford. Who also happens to represent Brian.

It's Club 328 that is providing our jet, and five minutes before our flight is due to depart, Max himself finally appears, looking dapper in his specs and Blake Carrington bouffe and performing a magnificent meet-and-greet that involves air-kissing a cluster of air-stewardesses, a brace of Barrys, and an important-looking person in gold epaulettes. And then we're off. Somebody appears to collect our bags and it's only when I see him sitting in the cockpit, I realise that he's the pilot. There's a delightfully homespun aspect to the operation. Morton, the first officer, pulls up the steps and then does the safety-and-comfort briefing.

'You'll find cold drinks under your seats,' he says, 'but if you have any questions just tap me on the shoulder.' Since he's also the co-pilot, I can't help thinking this is a Bad Idea.

But that's it. I have no boarding card. Nobody asked to see my passport. My luggage wasn't x-rayed. I'm just thinking that it's a pity I'm not an international drug smuggler with 20 kilos of horse in my bag, but Brian is starting to look agitated. 'Jaysus! It's like a tube of toothpaste with wings,' he says. He has a point. The jet, a Cessna Citation V, is roughly six metres long and just over a metre wide and there are six of us on board: Max, Brian, Mark, Suki, me and Jo, a smiley woman in her 40s wearing some impressive diamond jewellery who, for the purposes of this article, Max tells me, is his 'PA'.

'Of course,' I say, and think these 'PAs' really are the way forward.

It's at this point that I think I ought to try and formally interview Brian. It goes something like this:

'So, Brian, you're a celebrity. Tell me, how is it different travelling as a celebrity to travelling as a normal person?'

'Er, what? Like, it's, er, less time-consuming. Quicker, like.'

'And do you always use private jets?'

'If I'm going to Ireland I just get Aer Lingus or for long haul to Australia I'll go on BA or Qantas or whatever. But if it's short haul to Germany or something, I get a jet. It's a time thing. If I'm on tour or whatever, like, then you just have to be somewhere and you get a jet. I'm off to Australia tomorrow, though [to see Delta], and I'm flying with Qantas.'

'First class?'

'Yes, but the only reason I fly first class is for the leg room.'

'Yeah, right.'

'No, I once flew economy, and my knees were like this! We'd had like five gold records but the American record company had no idea who we were and, like, booked us economy. We had to get our own taxi from the airport and everything! I'll never forget that.'

'But Brian, that's how the rest of us travel all the time! You've never actually travelled as a normal person, have you?'

My line of questioning is, frankly, rubbish; but it's true, Brian has never been normal. He's spent his entire adult life on Planet Celeb. But at this point, some sandwiches appear ('You can't take a photo of me eating. I'm on the Atkins') and for a moment it seems a food fight might break out between Brian and Mark. It's impossible to dislike either of them. They're like a pair of over-exuberant toddlers.

I decide to pigeon-hole Max and hold my pen poised ready for the PR hard-sell. I've already checked the website so I know that Club 328 works like a timeshare. Any old Joe Bloggs can have their own private jet. Just so long as you have €328,000 (£225,000) - that'll buy you five hours of flying time and certain privileges to be taken whenever and wherever you want.

Max, though, seems keener to promote Max. After telling me how he could sink the Tories' chances of electoral success tomorrow, however, I'm given an insight into how the world of celebrity travel really works.

'Brian's a client of mine. Club 328 is a client of mine. Euromanx is a client of mine. Anything that I'm involved in always involves about five or six of my clients. At the launch tonight, I'll have other clients: investment banks, property developers, what-have-you. It all feeds into everything else.'

'Simon Cowell, a client, he's a member of Club 328 and there was a big profile of him that went out on American TV recently and he's seen flying on Club 328. You can't buy that sort of coverage. Of course, in return, he gets certain privileges.'

'So it's you scratch my back I'll scratch yours.'

'Exactly. We had to get Brian up to another client of ours, a hospital for sick children in Newcastle where the kids all live in these bubbles, and he wasn't going to be able to make it. Club 328 stepped in and provided the flight, and then we got some nice coverage of that in OK! and everybody wins.'

Brian, it transpires, doesn't pay Max a fee. But if he's told to turn up at three and fly to Galway, he does. Max has a house near Marbella and Club 328 flies him down there when he wants. Simon Cowell was drafted in to publicise the Isle of Man route. 'He doesn't actually have any connection with the Isle of Man but we came up with something.'

It reminds me of the line from Withnail and I, where Withnail explains the connection between money and privilege with regards to the 'borrowing' of Uncle Monty's cottage. 'Free for those who can afford it,' he says. 'Very expensive for those who can't.'

Brian and Simon have millions in the bank. It's a given that they won't actually have to pay for their private jets.

For which they actually have to thank us, me and Suki. It's because journalists write this stuff up and photographers take photos of celebs in front of corporate logos, that this whole thing works. And as I go and regain my seat, I have the tiniest inkling of how this works too.

'Carole,' calls Max down the plane. 'Do you like the sun? Would you like to come down to Marbella this summer? We do these concerts with Elton and Robbie, we could fly you down there. It'd be great fun.'

An hour later, we're in the limo on the way to the hotel, when Max takes a call from Caroline from the Mirror

'No, Caroline, Simon has not split up with Terri. He was still with her last week, he was still with her last night. Now, if you'd start writing nice stories about my clients, I'd invite you down to Marbella. We do these concerts with Elton and Robbie, you could come, you know.'

Four hours later, Brian and Max are on stage, and Brian has a 270-strong audience eating out of his hand. It's just him, an acoustic guitar, and a selection of songs including a new one, which Brian says, is 'for women in general' called 'It's a Lose-Lose Situation'. He's a natural, and I think that finally he makes sense.

Roisin, from the Galway Independent, who's sitting next to me, is less enraptured.

'Who'd like to accompany Brian on stage?' asks the compere.

'I'd rather eat my own arm!' says Roisin.

'I'd like to!' I say but then remember I don't know any of his songs.

'His songs are shite!' says Roisin.

'We're going to be holding a series of concerts down in Marbella this summer with Robbie and Elton,' Max tells the audience. 'And you can fly down there with Euromanx.'

Still, it's a great bash. Warren, the CEO of Euromanx, is wearing a white tux and sweeps me onto the dancefloor. 'Do you think this has all been worth it?' I ask him.

'We got the Irish Tourist Board and Galway airport to pay for most of it,' he says. 'And the local press love it.' I don't tell him about Roisin. It's a you-scratch-my-back-I'll-scratch-your-back kind of world, I can't help thinking. But hell. Galway will get more tourists. Brian will get his free flights. Max will make his 20 per cent. I'll write this article. Roisin will do her 'Brian Loves Galway' one. We, the travelling public, get £82 return tickets to the west of Ireland. It's a Win-Win Situation. What's not to like?

I go to bed at four, fail to hear my alarm call at six, and wake at nine to discover I've missed my private jet home. This is so incompetent but also so completely in character that I can't be bothered to give myself a hard time. I just think that I'd really like a PA.

I catch the Aer Arann turboprop into Luton instead. It's delayed for an hour and a half and I sit and drink coffee and watch the Pope's funeral live on Sky. A nun in the corner weeps. A child crawls past my seat and tries to eat my shoes. And, when I board the plane, I discover I'm sitting next to a nice Irish granny who's visiting London for the first time in 22 years. She tells me about her son who lives in Texas, her son who lives in Newcastle and her 48 years of being happily married.

'Only two to go before your golden wedding anniversary!' I say.

'Ah no,' she says. 'My husband passed away last year.' And her eyes fill up. Mine fill up too. 'I still miss him,' she says. 'I'm so sorry,' I say.

As I wave goodbye to her at the luggage carousel, and struggle through the crowd towards the bus, I can't help feeling glad I travel on Planet Pleb.

· Carole Cadwalladr is the author of The Family Tree (Doubleday). To order a copy for £12.34, with free UK p&p, call the Observer Books Service on 0870 836 0885.

How to travel in...

...Heat style

Appear in a TV soap opera. Acquire a drink problem/drug habit. Be photographed getting into a cab at Heathrow with the cellulite on your upper thigh on display. Check into the Priory. Lose three stone. Be photographed in a bikini on a beach in Barbados with your new reality TV boyfriend. Appear in a soap opera. Get a drink problem... and so on.

Role models Kerry Katona, Jade Goody.

Vogue style

Be propelled to stardom by a talent scout in a Chingford supermarket. Buy an Ursula Andress-style bikini. Be photographed falling out of it in St Tropez. Become best friends with Meg Gallagher. Fall out with Meg Gallagher. Date Robert de Niro until somebody points out that Jude Law is better looking. Marry Jude Law. Divorce Jude Law. Refind your inner serenity in a £3,000-a-night spa in the Maldives. Launch your own line of spa toiletries/underwear. Complain bitterly when people say it's overpriced rubbish. Refind your inner serenity at a £3,000-a-night spa in the Maldives etc.

Role models Kate Moss, Naomi Campbell, Sadie Frost, Sienna Miller.

OK! style

Marry a footballer/ageing Hollywood Lothario. Reproduce. Develop a signature 'Heathrow' style: eg jeans, heels and a low-cut top exposing your surprisingly pert and generous embonpoint despite the fact you've never had surgery, no, really you haven't. Pout. Be photographed by the paparazzi snogging your husband/lover on a beach at a prearranged time in a prearranged location. Complain when papped on a foreign beach at an un-prearranged time in an un-prearranged location. Sue the News of the World. Use the proceeds to purchase a Lear jet/small island off Australia. Live happily ever after. Until your husband dumps you/sleeps with a prostitute. Return to Go.

Role models Posh, Colleen, CZJ, Liz Hurley

Spectator style

Write/publish articles of the aren't-the-lower-classes-just-a-lot-of-
Burberry-wearing-chavs-with-no-sense-of-moral-probity? variety. Take a lover. Or two. Well, possibly three. Book a couple of charter flights to Mallorca. Be amazed/appalled when somebody spots your boyfriend's guide dog squatting in the aisle. Deny, deny, deny, confess that, yes, it's all true.

Role models Kimberley Fortier, Petronella Wyatt, Rod Liddle, Boris Johnson.

Factfile

For more information on Club 328 and how you can share the private-jet lifestyle, see www.club328.com; Euromanx (www.euromanx.com 0870 787 7879) flies to 14 destinations, including London City to Galway from £82 return including taxes.