In reply to b.hayley:
I spent a lot time some years ago on the Ile d'Oleron which is not far south of La Rochelle, and I asked around about bouldering but found nothing in the area. Someone on here might come up with something though.
Everyone in Charente Maritime was into sailing and surfing. Not much help to you I'm afraid. Beautiful area though, it is well worth visiting Venice Verte and also Oleron, especially if you like seafood.