For alloy wheel restoration, one of the best companies in the UK is Pristine, who are located at Woburn Sands which is just outside of Milton Keynes. The are OEM refurbishers and do work for major car companies such a Mercedes and Aston Martin. The often restore the all alloy wheels some of my customers Shelby vehicles use. As to the maintenance of the alloy rims, I recently located a clear laquer specifically designed to go onto polished aluminum surfaces. I have used this on my own 15inch Halibrands and the finish is superb. The downside is that you have to key the surface prior to applying the laquer which means some sort of surface scuffing to get that key. On my own wheels this preparation was done carefully and along the rim line so with the laquer applied the effect is lovely, however you do get a more satin finish which may not be to everyones taste.