Woah woah woah slow down and take it easy, don't jump in at the deep end before you can swim.
As others have said shoot some film first and have it developed by a lab, freecom2 first link has a list of UK labs, should at least be somewhere near you that can develop colour negative (C41 films) type films, scan them and give you a CD.
You want to
shoot a roll first to make sure your camera actually works properly, get a roll and shoot 36 frames of any old **** and get it developed, i and many people have been burned by dodgy cameras and lost good shots on the first roll because they didn't check it out first. Just ask dd1989 who shot five rolls before getting the first one developed and they were all blank, why? because he didn't know how to load the film on the take up spool properly, stupid yes, but a noob mistake and he wouldn't have lost a ton of shots if he just had the first roll developed and realised his mistake first.
If you have a C-41 lab near you great, stick to that for now before branching into real B&W or colour slide. You can buy B&W C-41 films, them being; Fuji 400CN, Kodak BW400CN and Ilford XP2 Super 400, if your lab is run by idiots they might refuse to process it but just insist that it's C-41 and tell them to STFU.
Though i'd just stick to colour for now, if you want cheap consumer film get a roll or two of Fuji Superia 200 or Kodak Gold 200 to blast through quickly. I personally prefer Kodak Ektar 100 and Kodak Portra 160 or 400 as they scan better for me and i prefer the look of them.
7dayshop's film sections are usually the nest place to buy film in the UK.
Once you've shot a few rolls you'll probably want to scan it yourself, if you only ever plan to shoot 35mm then get a dedicated 35mm film scanner like a Plustek 7400 or 7600i, if you plan to do medium format and want a more general purpose flatbed style scanner then get an Epson V500, both of these aren't cheap, about £160 for the Epson and closer to £200-250 for the Plustek, you can get a Epson V33 (not sure if that's the current model) for under a hundred but that's 35mm only when it comes to film.
Scanning is OK but can be a royal pain the arse, dust is the enemy, damn stuff is everywhere, it's time consuming, scanning a roll of 36 shots at 1200 or 2400dpi on a flatbed takes an hour before you even post process it, and you will have to post process it as scanner don't ever scan a shot right, contrast, white balance and other stuff will be off. If you can live with all that then scan away.
If at this point after a dozen or more rolls you like shooting film, how it looks, you've settled on your favourite film stocks and want to go down the old dark room route so you have more control over B&W development chemicals and making your own optical prints.
When you get to this stage then come back here and ask again, what's the rush?