Look up automotive paint suppliers to find your local supplier
or look for a company in Brighton who have a good reputation for mail order
(not used them myself as I have a good supplier 1/4 mile from where I work).
They should be able to mix any colour based on your paint code.
Home to black Alfa Romeo 159 3.2 V6 Q4 ,green MGF VVC and red MG Maestro T16.
MG - the friendly marque.