[matx1982]

I would do this...

Put the plate on retention now. This will take anything up to 2 or 3 weeks in my experience. Get the form from DVLA. They will issue you plates to put on that car which you'll have to get made, or if you have the originals still it's likely you'll get that reg back.

As soon as you have the retention certificate, give it to your dealer. They will register the car with that plate, so you don't have to then go to DVLA to change it over, you don't have to have new old plates made either.

Mat