The BBC Blast webpages have lots of information about writing scripts, film-making and directing, as well as an area to upload your own films (in addition to pages on music, dance, games, art, fashion and writing). They are also offering you a chance to have your film shown on BBC2 in December if you are between 13 and 19. You need to get a move on as the deadline is 17th October 2008.
If you are between 16 and 19 you can apply for a £3000 bursary to help you get started and work with industry professionals. This is an excellent opportunity for all budding film-makers, so please tell as many people as you can about it.