Halfords would be your best bet Valk, unless you need a specific colour. There's a company called Brown Brothers near me who will mixed any colour you want and put it in a rattle can if that helps. TBB. http://www.brownbrothers.com/
There's a place near me, auto paint suppliers, if you can take a part in they scan it and match the paint. And give it to you in rattle cans if you want L E Went 52-56 Burlington Rd, New Malden, KT3 4NA They did a good job matching the paint from the cowl on my Thrux so I could spray s helmet to match. Then again as said before. Halfords, they'll be cheaper