Once you have the V5 in your name, you will need to fax it to Customer Services who will then start the process (assuming that they are still doing the plaques). Time to receive varies, but typically about 3 - 6 months. No point in chasing, as the just tell you it will be on its way very shortly, or is waiting to be released etc....
The plaques are made by Creative FX after instruction from VW:
020 8313 1146 - info@fxuk.net
Creative FX
145 Masons Hill
Bromley
Kent
BR2 9HW
I hope this helps, good luck and enjoy your car!