Hi, Have you contacted Dublin Bus about the codes? If your not that fussy Halfords regularly do deals on the spray paints, the mad colours that don't sell sometimes at €2. I suggest you start with a primer, before you go filling, it will show up the imperfections and it will seal the wood and stop the paint sinking. Halfords sell a primer it's grand however check out Dealz, they do an excellent primer and also have other colours as well, take a look.
regards
Bren