This is truely the best stuff (on a sensible budget) that you can buy
http://www.cleanyourcar.co.uk/polish.../prod_351.html
Buy the scratch remover and the polish and a GOOD applicator (sponge to you or me) and you'll get bloody amazing results.
Mr Sheen will polish and make things look nice, same as many other products. (Tescos furniture polish is fine too) but will NOT remove suface scratches.
Anything 'Halfords' is generally better for drinking than it is for cleaning