Good French aires:
Sainte Mere Eglise, 30 mls south of Cherbourg on N13, diesel (1.29 ltr), motorhome station at petrol station; has SuprU and a ww2 museum, parking in village square at museum; shops yds away
Nozay is a very good aire, it's 194ms from Cherbourg on N137 south of Rennes, by a lake and local amenity park area, motorhome station in aire, (not brillant) couple of hundred yards from a good Super U which has diesel (1.32 ltr), wines to get you started and a motorhome station at the petrol station. CC entry ths year (5euros), whether you get electic point or not.
Mortagne-sur-Gironde 400 mls from Cherbourg off A10 (200 mls from Nozay) situated on Gironde estuary, lots of Motorhomes alongside the marina, very popular, need to get there early, 7.50 euros, whether you get electic or not, free access to Port wifi. Motorhome station at opp side of marina. Bread, frites, restaurants, etc at marina.
Buzet-sur-Baise, 535 mls from Cherbourg off A82 south of Bordeaux (135mls from Mortagne-sur-Gironde). Free aire at canal marina, water and toilets, electric only for boats, wifi from marina 2 euros. Next to quaint village with spar etc.
Hope this is useful to someone! Steadily heading south towards Spain!