patched up ceiling

We just removed the old shower and it's internal wall and the builder did a good job of patching the hole in the ceiling . However , I know that when the ceiling is painted the patch will become noticable . What should I do , try to sand oiut the marks ? are there products that apply a thick coat to cover up such blemishes ? would changing the light fitting ( get rid od white ball screwed to ceiling ) help?
All suggestions welcome

PJQ

Check out B&Q - I'm sure that I've seen that sort of product in there, but it was a while ago and i can't remember what it was called; one of the Polycell products?