http://www.satcure.co.uk/accs/page8.htm seems to have much lower
prices on
cables than anywhere else I've come across - anyone had any dealings
with
them? They suggest RG6 "for connecting additional TV sets via the RF
out
socket" which seems to indicate it's OK for UHF (though maybe not
low-loss?)

I expect someone will be along shortly who can answer on all points. In
the meantime, if you have not seen it already, you might care to read
Bill Wright's excellent (dare I say seminal?) article on cables
http://www.wrightsaerials.tv/coaxcablequalityhmdim.htm to see where RG6
stands in the rankings.

HTH

--
Robin