Paul. This to some degree depends on what you intend painting it with afterwards.
For myself, just as a primer, then a Halfords rattle can is good. Then u can use Halfords colours on top. This is no good if you want to use some other make of spray paint though.
If you intend using an enamel, Humbrol or something then the Halfords will be ok, but do not use if you want to use an acrylic. The word "Acrylic" seems to mean many things to many manufacturers….
Ashley