Op have you rattle canned a set of wheels before as its a right PITA to do property and they chip so easily. Plastidip is much easier and gives better results, but not sure they'll do the colour you want though. Powder coating is the way to go for look and durability.
Halfords mix paints. Got mine there recently. Got a code go see them. Bit more than £14 a can iirc.
Rover stone grey is incredibly close if you can't get the exact colour made up