I got mine done by fancy plates before my V750 (or whatever) came through. Took V750 to (not so) local DVLA (chelmsford) who gave me new tax disc, drove home, put the plates on next day. sorted.
That was december 2003
I was glad to getr the plates on just before i wnet on holiday - meant the car was parked up for two weeks off the road and outta sight, since i have heard of quite a few people having pork problems. Didnt someone on here have their car impounded coz plod hadn't updated their system and wouldnt beleive the DVLA paperwork? (funny now, but at the time i bet it wasn't!)
As far as spacing goes, dont take the P155 and you shouldnt have any problems. I've had traffic plod RIGHT up me jacksi and they've not batted an eyelid - then again i have legal font, legal spacing and all i've done is moved the groups around a bit