Thanks for your post.
While I have known people (including family members) with conditions somewhat similar to MSA (including Parkinson's disease), I haven't any specific knowledge or expertise in this area.
However, I was aware that there was a charity which was specifically set up to help people with MSA and a quick Google search reminded me of the name of it.
If you'll forgive a personal comment on what is primarily a factual forum, I would like to congratulate you on your attitude to your husband's difficulties. Far too many people would simply say "Well, that's it. My partner has got this disease, so we can never go on holiday again". Your obvious determination that you will both live as normal a life as possible demonstrates both strength of character and a true understanding of the best way to support your husband. (I hope that doesn't come across as 'patronising'. I can assure you that it's sincerely meant).
I hope that you will have a really wonderful time together in France.
Chris