Aire de Service near to Mont St. Michel?

Sunlovers44

Hi folks, we're looking to travel from Calais through to the Vendee coast and back up towards Brittany in mid-September and are keen to explore around Mont St. Michel as we come back up heading towards Calais. Has anyone got any suggestions for motorhome
(aire de service) stops near to the area, or failing that, campsites suitable for a 25' unit?