jenniffer, if you're just getting started on the rather long and arduous road of filmmaking, here's a couple places to start:
1) watch a LOT of documentary films, not only modern-day ones but especially some of the older docs. if you google "top-ten documentaries", you'll find a lot of lists from which you can begin watching. there are a lot of different styles of documentary, so pay attention to whichever style suits your personality best.
2) read Michael Rabiger's "Directing the Documentary". there's quite a few doc books out there now (one by Hampe, another by Rosenthal), but Rabiger's is the best by far. a local library might have it, but most bookstores won't.
3) find a subject that you are absolutely passionate about. don't pick a subject that you think OTHER PEOPLE will find interesting – it has to be interesting and compelling to you, enough so that after three years of shooting, and two years of editing, you will still persevere with it.
4) Go to a local community college (or whatever they have in the UK) and take some cheap camera and editing courses. you don't have to become a pro at either, but you do have to understand the basics of proper technique.
5) Good luck!