Removing all the crap off the paintwork will help alot - ie decon with iron x/purple rain, and then a good claying will improve it alot, you can now polish the paintwork back. The halfords polishers arent the best - you dont get any cutting pads with them - its just like using a microfibre cloth real fast and relying on whichever product you are using to the work. Ideally a dual action polisher (DAS6) and some decent polishing pads will work wonders (as shown above). All depends on how much you want to spend how keen you are on doing it yourself, dor a DA, pads and polishes your looking around £130-140 - a little bit more than you would pay for a good mop, but least you have the gear then for the future. Blue maskign tape can be bought off ebay, use the 3m stuff though, i got some cheap ones off ebay and they arent as sticky and lift very easy.