Hi Shepherdqueen
My husband has MS and we just returned from two weeks in London. He uses a mobility scooter to get around. Vacations are very doable with an MS dx, but proper planning is so important. We have had to adjust the way we travel over the years to accommodate his disability as it progresses.
When we go to Cape Cod in the hot summer months, he makes sure to take cooling hats, drink lots of water, and take frequent breaks. If we are walking down to the beach, we choose a place that has a boardwalk or other structure so he is not walking on sand the whole way down.
I would check with Royal's Guest Assistance before your trip. They deal with these issues all the time and I'm sure they will be able to give you a lot of good tips and advise on how to navigate their island. Also, there are a ton of private MS groups on facebook that you may want to consider joining. My husband belongs to one and I belong to a different one for "caretakers" of people with MS. It is so awesome having people in your shoes to talk with.
All the best.
Tracy