Or do you have a friend who might take a second car to the airport for you and the same on return? If you live close to Gatwick, and are flying with Virgin, and can make use of the twilight checkin that would help as it would be possible to take your cases one night and then go back in the morning with just hand luggage and the wheelchair and walker. I know it's a bit of a long shot and would mean 2 trips to the airport, but could solve the problem.