Norman
Halfords do a clear satin and a clear gloss spray, both of which I have used over their own paints. HOWEVER there's 'acrylic' and then there's 'acrylic'; the type of solvent is the important difference. As always, you should try them out on a scrap piece first or your fully-dried Tamiya paint may suddenly go soft and crinkly.
I have no idea if they also do a matt but that finish often looks too flat on a model boat.
Dave M