French on route campsites open late September

HomeForStrays

 Hello hope someone can help. We have planned our first touring adventure to France for all of September. Just found out that lots of campsites close down by the middle of September! Help ! We have found sites open in the Dordogne which suit us but we have
no idea of how to get back to ferry from Sarlat-la-Caneda to (Quistreham) Caen. We plan to take 2 on route overnight stops and spend the 3rd night at Quistreham for early ferry to Portsmouth at end of September. Can anyone please suggest the best route back
to ferry and most importantly some stopover sites likely to be open then.