We have never cruised with Fred Olsen but can highly recommend P & O. My husband is a full-time wheelchair user and we have had some wonderful holidays cruising with them. You will find plenty of other disabled people cruising and they organise shuttle buses in some ports for disabled. Don't let being in a wheelchair stop you from enjoying yourself. Happy cruising.
We travel with Fred annually and I take my mother who is in a wheelchair, I can say the staff are so helpfull it is a pleasure to go on board.