You can get a number plate through an ebay site and they only charge £11, we got one, they are legal. Best thing is you don't need any documents.
Jaymo
Technicaly it would be ilegal to use a plate made without the production of documents. and if you use a site like the other one to create your personalised plates with out the legal spacing you could loose the rights to your number plate and have to pay to reregister your vehicle. The DVLA and police are getting hoter on this
"sticky" make it yourself are legal on trailers manufactured prrior to sometime in the mid 90s (96 I think, but research yourself to be certain) I have stickys on both vans and never had any complaints from the men in the blue & yellow volvos, however when the proper plate on the race trailer was cracked i barely got 5 miles before a passing cop at traffic lights suggested getting it fixed