It's near St. Gilles Croix de Vie / Sion south of Nantes - the place is called Le Pas Opton.
We stayed in St Gilles in 2006 - a french friend of ours lived there and we were out there during the Tour so I caught the TT stage at Rennes. I can recommend Lac De Jaunay which is a bit inland. Lovely for picnics and swimming if you want to escape the crowds..
Try Matthew's Bistro... lovely grub!A week on sat I am spending a week in Keswick with numerous walks planned then in Sept I am in Ambleside for a week of walking and boozing, in no real order.