There are, or were, several stores in London selling used super-8 and 16mm cameras (note: they're not camcorders, they're film cameras). The Widescreen Centre ( http://www.widescreen-centre.co.uk/) is one place we've used in the past, though I haven't been there for several years.

Picture quality is quite decent for 16mm even when projected in a cinema, super-8 is a bit iffy, but still better than video (I've seen super-8 projected on an IMAX screen and the grain was literally the size of footballs). However, the choice of super-8 film stocks is limited and neither a cheap 16mm or cheap super-8 camera is likely to be quiet enough or well synced enough to record sound at the same time. The last super-8 short I edited the sound was recorded wild on the set and we had to build the soundtrack up manually because the camera quickly got out of sync with the DAT.