Most of the information on index funds that has been provided in this thread, and in links from this thread, is applicable to the UK. I suspect all the information you're likely to retain, and need, is applicable.
Here is a quick-and-dirty document I threw together for London LWers looking to invest in index funds but not knowing where to start. There are better guides out there but they are necessarily longer. Googling "UK index tracker" will get you quite far.
I think it's past time for another Stupid Questions thread, so here we go.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Please respect people trying to fix any ignorance they might have, rather than mocking that ignorance.