All modern ships have good access and facilities for wheelchair users including special rooms.The Berlitz guide will give you a rating for the best ships,But please remember that not all port have good disabled facilities so maybe consider sailing from a UK port where they have plenty of help and close to the ship parking,RCI would be my recommendation but out of the school holidays,best of luck?
You do not say what your question is other than with mobility. Arcadia with P & O are very very good with people with mobility problems and look after them well.
I would suggest one should avoid the family orientated ships as the staff did not seem as empathetic. P & O will send you a questionnaire as to your mobility problems and requirements. Be Honest - remember you cannot bleat afterwards if you are not direct in your dealing with the company. Bon Voyage!
There can be major problems. You need to consider this on a ship-by-ship basis and check bathrooms, public areas etc. I have had to do this.
On some ships it can be very difficult transfering to land from the boat by tender (i.e. a smaller boat).