Can't help with the air brushing I have enough trouble brushing my own hair lol Have you thought about printing it on sticky back vinyl A4 sheets are cheap on ebay
Best thing I can think of would be to ring a custom car shop or similar. they usually have all the gear and someone or will know someone with the airbrush skills to do what you want. and its not a whole bunch different painting a PC case to a Car im guessing. Have you tried that?
here's a couple of UK based sites : insanarty and liquidcolourdesign You could also try asking on some Airbrushing forums, I'm sure there would be some that have UK members that could help out, failing that if you live near a University there might be some creative types that are handy with an airbrush.
Google for "Airbrush Studio UK": www.airbrushperfections.com www.airyarts.com www.kustomflow.co.uk www.cain-airbrush.co.uk www.jotaylor.uk.com
