If it helps, I've just transferred the plate from my old car onto my new one and it took about 5 days. Quite quick, really. I haven't had my new V5 through, yet, but on the vehicle check page on the DVLA website the plate is now assigned to the Golf, so I've put the number on and had no problems.

you need to fill in this form;

https://www.gov.uk/government/upload...317_150814.pdf

and send it to them.