You can order from any Motability dealer anywhere in the UK, as ong as you are willing to travell once to order the car and again to collect it!
If you are able to find a dealer with a car in stock they are willing to let go to a Motability customer, you could let the garnts team know, but without being assigned a grants manager to your case its likely to fall on ddeath earss. They can also be a funny breed of people lol.
I would be inclined to to reng Motability and ask if you can have access to cars ready to go:
https://readytogo.motability.co.uk/
Motability are also offering a new vehicle payment of £750 to new and existing customers providing you order a car before the end of 2023. You can also use your Golf as part exchange towards the advance payment f a motability car. You may find you have £1000 or more, you can use as payment, which may put you you in a suitable car on the scheme. Its another option rather than waiting an age for the grants team to contact you and a shame if you lost out on the new vehicle payment just because grants dauldeled!