Hi all,
I recently sprung a leak on the dreaded left hand rad, and after some very scary quotes from various people (£270 plus vat to recore ffs), I found this place who are repairing it for £107 all in (vat & delivery etc):
http://www.gmxradiators.co.uk/
I should get it back this week so unless it comes back in a complete mess I'd recomend them.