Hello,
We face the same challenge.
Previously we have taken holidays in Ireland - rent a house on the grounds of Waterford Castle for example, was very enjoyable (although could prove expensive).
There are facilities to take your dog by ferry, to both the UK and France. However, certain conditions apply, such as requirement for a "Pet Passport" and restricting the dogs movement to small kennel type units, or your vehicle, for the journey.
Information can be found, on both Irish Ferries and Celtic Link Ferries websites - perhaps also others, but I've only reviewed these two providers.
We have quite a large and energetic dog, who needs exercise and I would have concerns about either (i) leaving him in our car for a long ferry crossing to France, or (ii) in a small enclosed kennel, where there are restrictions on access and the dog may become stressed and react badly. Obviously, I would appreciate comments on both of these concerns, from other dog owners who have had to address similar concerns.
Having travelled to either Britain or France, consideration must then be given to such issues as their requirements for muzzels (which can differ to Ireland for certain breeds), what facilities the accomodation you are staying at offer etc. No doubt there are websites which list Dog-friendly locations, in both Britain and France, but I have yet to review or use them and again, would welcome comments from others with experience.
Hope this helps.
Regards
Mr. Earl.