As regards a UK supplier of Rollei lenses, the name you'll usually hear is:Robert White
Otherwise, I second the eBay thing. I've just picked up a used (Mint-) 110mm/f2 for £1000 - a snip given that the 'new' price in the UK is around £3900. Apparently, only 500 of the f2 were ever made (can anyone confirm?), but that aside, I'm happy to have gotten hold of one - beautiful bokeh!
From what I've been told, Zeiss no longer make glass for Rollei/Hy6 in its varying guises, so any of the Zeiss lenses out there are "as long as stock lasts". Again, I'm happy to be corrected on this!
Best wishes all,