We've found this company a good source of second hand equipment and very helpful:
Kay Optical UK- Binoculars - Telescopes - Microscopes - Night Vision Astroscopes - Optical Instruments - Sales, Overhauled, Serviced & Repaired
As it happens we were looking for another second hand scope to replace the one we already have from them (nothing wrong with it, just want a better one) and they seem to have some decent deals.