If your husband is ill, I would certanly NOT consider moving to France (or any other country).
I will be blunt here, but if you have to look after him AND the dogs, and you dont like sun, I think he is being rather selfish asking you to move to France.
You dont say what his ilness is, but suppose it gets worse in France and he has to be rushed to a specialist hospital.
You will have to go with him, and who will then look after the dogs.
Sorry, but if he wanted to live in France he should have gone in his 40s or 50s.
Going in your 70s (with him ill as well) is a VERY bad idea.
Just put your foot down and say you are not going.
All this is on top of the comment jake made above which is an extra consideration.