Presumably you’ve booked already? Where? How?
We went to Brittany for a long weekend last year, for a friend’s birthday. The only info I can pass on is that Brittany Ferries are pretty well set up to receive and accommodate wheelchair users- from allowing yo to park your car by the lift, with plenty of space for getting the chair out of the boot, and getting into it from the passenger door. The cabin was just about managable, though I think those with less upper body strength would strggle with the berths. We stayed in a gite that was just about manageable for me, arranged by the birthday girl who had local knowledge. We weren’t there long enouh to find out how well France is set up for us in general.
In this country we go to great lengths to check that the accommodation is suitable- access, bedroom set up, bathroom set up. Most adverts aren’t detailed enough, so we just pester by email and phone for details and pictures.