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P & O have an arrangement on arrival by car you drive into the terminal "drop-off" which is by the passenger entrance. I would think it will be best to have requested a wheelchair when booking, or, at least before you arrive. Your car is then driven by their staff to wherever it stays for the time away on the cruise - which will be as near as possible to where the ship will dock on return. I would think other cruise companies will have someting similar available.