You can get stock vehicles but takes some effort on your part.
I made a list of cars on the scheme I liked, and fitted my needs, and started calling round dealers. I wasn’t overly fussy, just needed a car (was without one) that I could get into, sit in comfortably, and fit equipment in. (A higher car, with decent back support and a large boot).
Called a few dealerships and explained I was a motability customer, all were quoting a 12 month wait.
I called my local nissan dealership, and they offered me a stock qashqai. That was on the 11th November.
Went in that day to do initial paperwork and look at car, and picked it up and drove it away on the 16th.
Please don’t go in pretending to be a private customer – it’s a waste of your time and makes it less likely the dealer will offer you a stock car.