TiVo was the first UK PVR available amd is still IMO the best. It can do most of what Sky+ does except it can only record/display a single channel at a time and records an analogue signal.
TiVo requires either a £10 per month or £200 lifetime (of the box) subscription to get the full functionallity. Without the sub you can still use it as a dumb digital recorder, but loose most of the PVR type functions.
The official UK TiVo web site is
Here but you will get far more info from the
TiVo Community, just go to the UK section.
Mark.