Autoglym is quite good stuff, but over priced. As with everything, once it gets a mainstream rep, it becomes overpriced, same with Megs now. IMO Dodo Juice do fantastic products and although can be a bit pricey, they are well worth it. I'm with Stew, try Lime Prime (or Lite if you want no cut).
Remember to tape off any plastic bits near to where you are polishing and to wax or seal the car afterwards to protect your nice shiney paint work.
Also check out DetailingWorld - http://www.detailingworld.co.uk/ - for guides on how to do it properly. IMO the biggest factor to keeping a good shine is washing properly with the 2BM method as it keeps the paint swirl free. Any small scratches you inflict in the paint ultimately detract from the shine which no wax will be able to get you back Also if you can stretch to it, get your car machine polished by a pro, well worth the effort and cost. You could spend way more on differnt products to get a shine that they can get in a few hours working on your baby