If you head down south would recommend Lac D'Hourtin on the Atlantic side,there is a resort for schools that is deserted in september so can wild camp next to the lake,only a couple of miles from the surfing beach of Carcans as well.On the Med side we had a lovely few days at Lac Du Salagou near Montpelier,no camping overnight directly next to the lake but aires and campsites scattered around it,both remarkable mozzie free when we stayed a few years back