Sussex Model Centre appears to have a pretty broad selection of items unique to your area as well as items we can buy in the US. This link should take you to the "trainers" category.
http://www.sussex-model-centre.co.uk...2&cat=trainers

If you go with glow power, Just Engines http://www.justengines.unseen.org/ is a UK source for engines, mufflers, etc that has a good reputation on RCU.

Check the British Model Flying Association http://www.bmfa.org/ site for info specific to the UK. Finding a flying club, or at least other local flyers, can be a great source of advice and maybe even a super deal on some equipment.