If you do it yourself, you will have to clean the chip out fill it with paint, i find a tooh pick good for this. And then let it dry for a couple of days. Rub it down using some mild rubbing compound G3 or something untill the stonechip is flat with the rest of the paint around it. Apply a ploish of your choice and buff it up to nice shine. But to be honest £70 isn't much, and i would personaly give it to the body shop to do. As they'll have all the gear and might get better results