hi mate,
the general rule of thumb with scratches is if you can feel it with your fingernail it needs to be proffessionally done.
the best scratch remover product i have found is ;
brand name - "meguiars"
product name - "scratch x"
comes in a black tube, and is available from halfords, most car spares shops as meguiars have a range of products such as polishes, various cleaners, a u.s company - famous for making very good products for many years and with a good reputation,
the product in question will cost �8.99- 9.99.
involves some hard rubbing but i have found it to work.
pretty much the best one on the market.
;)
hope that helps.