The UK has 19 reactors generating one fifth of its electricity and all but one of these will be retired by 2023.  New-generation plants are expected to be on line about 2017.

UK’s first commercial nuclear power reactor began operating in 1956.
It has full fuel cycle facilities including major reprocessing plants.
Government commitment to the future of nuclear energy is firm due to energy security concerns as current reactors approach the end of operating lives, and the need to limit CO2 emissions. 
UK electricity production is 398 billion kWh gross, from 83 GWe capacity. Net imports are about 8 TWh, from France. Annual final consumption is 343 TWh, or about 5660 kWh/person.
In 2006 UK nuclear plants generated 19% of UK electricity (69 billion kWh of some 380 billion kWh net), compared with 36% from gas and 38% from coal.  In 2007 this dropped to 15% (57.5 TWh) and in 2008 it dropped further to 19.2 TWh for the six months to end of September due to problems with some old plant.  There are 19 UK reactors totalling 11 GWe capacity. In addition, about 3% of UK electricity demand is met by imports of nuclear power from France, so overall nuclear total in UK consumption is normally about 22%.

A target of reducing UK greenhouse gas emissions by 80% by 2050 was announced by the government in October 2008, along with the observation that nuclear power would be essential to have any hope of achieving this.  Government ministers and advisers have canvassed 40% nuclear supply as realistic and desirable, though the government has not gone beyond replacement (20%) as policy target.  (The 40% in 2030 would be some 200 TWh requiring about 30 GWe of nuclear capacity.)

You can download the  full Nuclear Power in the United Kingdom report here.