I went to a bodyshop for the work I needed done to my old car because it was a lot more extensive than what Halfords could have managed, and I'll be going back to the bodyshop for the repair to my current car because I know he does a good job. If it's a bit beat up anyway and it's only a small scratch, take it to Halfords, I think they can actually do the spray job for you. Might be worth getting a quote from the bodyshop if you'd prefer.