I'm not sure what you would do there without a car.
Hire one!
I've done fly-drive and drive (towing the home on wheels) to that part of the world many times. Nice towns (Les Sables, St. Gilles, La Rochelle itself, Benodet, Quimper, Concarneau - last 3 a bit further north in southern Brittany) and great beaches, countryside.
Packed with Brits, Irish, Dutch, Germans (and a few French) during the Summer hols.
RYR and EZY aswell as BEE fly to LRH if I'm not mistaken from various points.