• I'd strongly recommend taking a night-ferry to somewhere like Caen or St Malo; it will feel like much more of a slog from the more northerly Channel ports. Avoiding the exhaustingly hilly Massif Central, your broad options are then either to head due south, cutting through to the Mediterranean along the line of the Canal du Midi, or to head over to the Rhone-Saône valley, perhaps via the Loire. As a a first-timer and for sheer breadth of choice, I'd suggest the former.
The key to pleasant riding is to follow as far as possible the departmental roads shown in yellow on most maps: almost always well-maintained, direct and with what traffic there is refreshingly considerate to cyclists. I find the IGN 1:250,000 maps ideal, showing the terrain far better than Michelin's nearest equivalent: you'll need half a dozen to cover your route.
You can take your luck with campsites, though I find carrying a copy of the Michelin Camping-Caravanning guide invaluable towards the end of each day. Ignore any recommendations to book ahead in the holiday season, though - you need to be able to follow the mood of the day, and as a cyclist you're unlikely not to find space.
From the ports suggested, and if you stick to your 50-miles-a-day, I'd allow ten days or so in all. Bonne route!
Nat Goodden
• The Cyclists Touring Club have a touring information department who can send out detailed information on cycle touring routes in many areas, based on reports which they have received from members who have toured there previously. If you're not already a CTC member you would need to join to use this service, but having done so you would have access not only to touring advice but also to good deals on insurance, clothing and equipment and technical advice for your trip. CTC are on 01483 417217.