You mean self-adhesive vinyl? Just answered this question elsewhere - the only people likely to offer it is Fablon, in plain black, and you'll have to contact them directly for sizes over 900mm wide.
Arcadestickers.co.uk do side-art, but only up to a certain width (30" if I remember correctly), though unfortunately when I was submitting orders for customer's side-artwork for our cabinets, they stopped answering my e-mails so don't know whether it was a communication issue or lack of professionalism. I have been searching for a reasonably-priced alternative in the UK for a long time but they are all too expensive with long lead times - your best bet is to go direct to gameongraphics.com (formerly mamemarquees.com) in the US, as it actually works out cheaper than the few UK suppliers and is usually here in under 2 weeks anyway.