The only thing you need to have to do with halfrauds is to go in and purchase their number plate sticky pads... dont give them buggers the money for a simple job!!
With the old plates off, just make sure you clean the surface properly so they can get decent adhesion.. also, allow them to fully cure for 24hours if you can before you take the car anywhere, just so to prevent dibble chapping your window when your out and about, saying that they're pretty strong so even a couple of hours should be ok..
Theres two different thickness, 1mm pad and 6mm pads.
I've got the 1mm's on both front and rear, just make sure you line them up correctly before you press them home.. also make sure its not like -40 outside!
When it comes to removing the plates, just get some dental floss and run it behind the plate and it should lift off the car no problems. if you then want to clean the remnants of the pads off the plate/car, i've used AutoGlym intensive tar remover and its worked a treat!