Hmm, i recently watched Nil by Mouth, which i loved, terrifying, disturbing and horrible, but yet somehow just brilliant, and so is first in my mind.
sidenote: ray winstone in that film is the only character i've been scared of in a film (been scared BY films, but not by characters in films)
this is not a love song - a modern retelling of "of mice and men" and a bloody good one at that.
28 days later, the first half of that film is the best zombie (yeah they aren't zombies but whatever) film ever created, second half is meh, and really its not all that indie, but deserved to be mentioned. (same as shaun of the dead)
moving away from british cinema, Breathless (/a bout de souffle) is a great film, made purely for the sake of making a fun film.(and breaks just about every "rule" of cinema)
also: i hate ken loach.
Edit: a scanner darkly