You have to be careful what you write as a journalist. A careless sentence can land you in court or, in my case, in the members' enclosure at Sandown Park racecourse.

It came about because of a throwaway sentence in a piece I wrote for Escape about the pleasures of visiting Egham, on the western edge of London, and being able to walk along the banks of the Thames. I said that for those who like more expensive pleasures, there were also several racecourses in the vicinity.

I have to be honest and say I had no idea whether going to the races was expensive, cheap, or somewhere in between. My knowledge of life alongside the track was restricted to a scene from My Fair Lady and a Marx Brothers' film. I suppose I expected an enclosure full of men in pork pie hats and tweed jackets, carrying expensive binoculars, and women dressed like Christine Hamilton. Any children who wandered in by mistake would, I imagined, be in severe danger of being served up for lunch.

However, United Racecourses, which owns most of the big London tracks, is in the middle of a drive to try to project racing as a cheap, accessible and family-friendly day out. That is why their publicity people called me out of the blue, and why I turned out on a Saturday morning, with my wife and two young daughters, at Sandown Park, near Esher, Surrey. It was the day of the Whitbread Cup, a big event in the racing calendar. The Queen Mum was there.

There is a strange rhythm to watching the races. It is not at all like football, though for short bursts, as the horses are heading for the winning line, the spectators become like soccer fans, shouting at their nags to hurry along. After these flashes of intense excitement, all goes calm suddenly, and the terraces empty as everyone crowds into the cafés or queues to collect their winnings.

Shouting at your horse to hurry along is an aspect of racegoing with which we are culturally familiar, because of the famous line in which Eliza Doolittle uttered the word 'arse', and nudged back the frontier of theatre censorship. But it is pointless. Neither horse nor jockey can possibly distinguish the shouts of their supporters from anyone else's. In the main race, when the winner was far enough out in front to be jumping fences alone, it is possible that the jockey could tell that the applause was for him alone, and that he was encouraged - and the rest of the pack discouraged by it - but I doubt it. Generally, all the noise can do is egg on all the runners indiscriminately.

There was one amiable exception to this rule. When a horse lagged spectacularly far behind, there would be an ironic round of applause as it ambled by. Then the jockey would certainly know that this was for him, but whether it helped, I could not say.

I don't know to what extent our girls, aged eight and six, could be said to have been exposed to the pleasures and pitfalls of gambling that day. They certainly had a good time, because we opted for a family-friendly system of picking winners, which I would not commend to anyone who wants to get rich. Basically, the girls looked at the list of runners and picked out the name which appealed most to them. They called it 'voting' for a horse.

You will not be astonished to know that by this democratic means, we blew all our complimentary vouchers on losers. But because the vouchers were given to us by Juliet, the racecourse company's public relations officer, it was their money if we lost, and ours if we won. Losing was the only decent thing to do. However, by the time our vouchers had run out and we took to betting with real money, we had picked up on the fact that there is enough useful information in the official guide to steer you away from foolish bets. I'm half ashamed to admit that we left carrying more money than we had brought with us, so our day was just about cost free.

Unfortunately, most people cannot go in as guests of the PR department, and therefore must part with some money. Nonetheless, it need not be as hard on the pocket as you might expect. Entrance is free for children under 16, so the only money you have to pay is the entrance fee for adults, which can be as low as £5 a head. Once inside, the refreshments are not cheap. The ice creams, for example, were £1.50 each. But you are not obliged to buy: you can bring your own picnic if you like.

The courses make a point of welcoming families with children. Three days in the Sandown Park calendar are designated family days, with clowns, jugglers, free pony rides, face painters and a roving jazz band. They have half a dozen such days at nearby Kempton Park. At all race meetings at both tracks, there is a free crèche for children under five, run by qualified staff. Although the day we were there was not a children's day, it was rounded off by a free rock concert. Despite the fact that there were two stag parties in progress, by my count, only two revellers had to be carried out for being objectionably legless. Not like a football crowd at all.