Chazzer,you are correct that the BP truckstop is now closed.Popularly known as the cabbage patch.May soon become a hypermarket,if not already.The one by La Rochelle was Aire de Marins (I think) otherwise known as the Fish Restaurant.Excellent place to stop.Coming home I stopped at the one just off the roundabout after La Rochelle a few times,good food,friendly place-but can not remember what it was called! 
Also,Barbezieux -weekended there a couple of times in the summertime,lovely to walk down to the little lake to cool off and lie in the sun. 