Here in Norfolk we have local branches of the Red Cross who will provide wheelchairs on a short term basis - at no charge - providing person is considered in need and one is available of course.
My wife did her achilles tendon in a few years ago and we got a wheel chair free from our local council and after she passes her shopmobility test on a motorised wheelchair she used the local shopping centres machines of a Saturday. I think they took donations for that but it was worth it. Ask around Mischief