Definitely check out what your friend has. If you do have to buy new stuff, post questions here about what you're looking at.

This company has been mentioned as a good one to deal with in the UK.
http://www.sussex-model-centre.co.uk/
The web site was down this morning but has the phone number listed.

Slough Radio Control Models came up in a Yahoo search for UK Hobby Shops
http://www.srcm.co.uk/system/index.html
None of the ARF trainer planes they have listed are marketed in the US but they look just like the ones we can buy. The primary one they have is the Irvine Tutor 40.

Here’s a source of engines, and engine parts, that gets good comments for customer service.
http://www.justengines.unseen.org/