cant help with site suggestions but its a popular area so people will be along soon with their recommendations. Meantime have a look here for advice for first timers abroad.
I would recommend Ty nadan in Brittany - but it's not near the beach - 20 mins drive. It has got indoor and outdoor pools and lots of activities for the whole family. It has a small river where they do canoeing etc.
For a good beach holiday try Vendee a bit further down but worth the drive and lots of good camp sites.
If you are going to Brittany, or the Vendee, use the St Malo/Caen/Roscoff ferries and not Calais - it will cost a bit more but save many hours driving.
We usually book through C & CC Carefree service and they have been really efficient and we always get the best pitches on the site for a good price!
Carnac is nice on the west coast. Nice site called plijadur in trinite sur mer. Clling in this August for 5 days.Beach at Carnac is nice . Loads of sites in carnac. Plijadur has a website www.parkplijadur.com we are paying 14 euros per night. Worth a look.
Don
------------- Don Hooley
Don't forget to leave a review of the French and other European campsites you have visited!
we've stayed here http://www.kervel.com. Smallish site, pools with slides, bar, take away, table tennis, childrens playground etc. Within walking distance of a great beach. Not too noisy but offers some entetainment in the high season, Claire
Try L'atlantique at Beg Meil, good pool complex and near to a lovely beach, you walk through a nature reserve at the back of the campsite to a lovely sandy beach. Quiet a big site but should be quieter out of high season. Only downside is that you have to drive to nearest shops and restaurants, but Fousanant is a nice town with a biggish supermarket and lots of nice beaches with plenty of rock pools, only other downside is the weather,similiar climate to Cornwall so you maybe luckly and have 2 weeks of glorious sunshine or!!!! if you are worried about the weather it maybe worth venturing further south to the Vendee.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.