First time to France - should we take dog?

We have booked to go to France - Du Poulquer, Benodet, for the first time in August. We can't decide whether to take the dog (Staffordshire Bull Terrier) or leave him with family.  Our main concerns are the ferry trip - Plymouth to Roscoff, although he does travel quite well in a cage in the car, and also if we can take him on beaches.  Any advice would be very much appreciated.