Not so long ago Motability Operations were setting up a pilot area of the website showing only cars immediately available. May be worth giving them a call to see if you can join . If you don’t like the answer you get the first time call back later. It is sometimes the luck of the draw as to how much the call handler you connect to knows.
Pretty much an impossible task, even dealerships struggle to keep up to date and there is a need for Motability to have a link direct into the manufacturer system to enable this to work. It is definitely a great idea but the nature of the challenge means it will never happen. Ready to Go was a trial BUT with a very limited choice of cars. Best solution is a bit of leg work ourselves 🙂