This is what you need mush. Halfords do them.. All you need to know is the year make and model of your car and the paint code.
It's a three part system. Primer, top coat and laquer. It *should* also come with a pen to prepare the area IIRC.
However, know that what they will basically do is fill the scratches with some over run. So you then (once the scratch is full of the paint) buff it off with some Tcut to level it out.
It won't be perfect (due to your paint being three years old and no doubt a slightly different colour to new) but it does work quite well. My mate has an M3 in metallic black and we managed to do a pretty good job of a scratch on his bonnet. We even got a couple of scabs on the arches passable