Lee, your last but one post says you can't have an old plate.
Yes you can, but in th first instance the car will (hopefully) be given a new reg, and then you transfer on to the car a classic plate.
Fred, go to google.co.uk and do a search on 'show plates'. You will get pages of hits.
I've personally used :
My Showplates - Design your own show plates Welcome to No1showplates - Number Plates and Show Plates Classic plates and Vintage Embossed Number Plates
plus a few others who's links I don't have.
Hope that helps.