I'm not a body boarder ... this body is strictly land based and preferably seated! ... but the beaches of SW Vendee are particularly good for yachting because there's lots of wind. You might try the beaches south of La Rochelle (Les Minimes) or Fouras. By the time you've got to the Bordeaux estuary it quietens down, but you might like to look below the Bay of Arcachon (south of Pyla Plage) for suitable areas too, even though this is now Aquitaine rather than the Vendee.

Has 'Nautisme Vendee' given you any help as regards a Google? Might be worth a try! Don't forget that the wind and the sun can burn you.