In March 2021 I managed to find a brand new Peugeot 5008 in stock and picked it up within 2 weeks. My tactic was to search Autotrader for new cars with photos of the actual car to show they had it in stock. Most new cars on Autotrader just have stock pictures which means the car will in most cases be a factory order. Once I had found a few I emailed the dealers about getting the car on Motability. Of course you will have less choice of colours and added options but you may get a car much quicker.
Good luck.