Have look on here Mr. Entwood see which ones you think 
http://www.eurocamp.co.uk/
Looking at the France - southern vendee part of that site .. I've stayed in several of those towns
La Tranche ... Full of tourists .. and caters for them.. . gets a bit frustrating
St Julien des Landes ... really quiet, rural place (good bakery though!!) about 20 minute drive to the coast. we actually visited that site from where we were having made some friends in town .. huge site with just about everything you need.
St Jean Des Monts .. right by the coast, roads get a bit busy, lots of nice bars and restaurants
From any of those places it is an easy drive to one of the massive LeClerc hypermarkets for shopping, which is always cheaper than buying "on site"
That part of France is an easy trip down from St Malo in a day .. even with the 'van on the back .. so solo its no problem .
