Ok, noticed a small chip (about 2mm) that's started to rust a bit and it's annoying me so I want to sort it asap. What's a decent anti rust formula that I can go and get today? Preferably something that Halfords stock.
Aye, I'm planning on painting over it once done, the only reason I don't want to sand is like you said, I don't want to damage the paint around the chip which will probably happen with it being such a small area.
In which case you are unlikely to kill all the rust, as it will have crept underneath the paint surrounding the chip by now.