Living in a Sharehouse
The easier and more common option is to rent out a bed or room in an already established flat. Usually there will already be an ongoing lease in place and sometimes the leaseholders might no longer even live at the house. Sharehouses tend to go through a lot of occupants and you'll probably pay your bond to the person whose bed you're taking and be required to fill your bed when you're ready to leave in order to get your own bond back.
Chances are good that you'll probably spend most of your time away from work with your housemates and that they're the ones who'll become your good friends in London, so take a bit of time to make sure you'll get along with them. You should definately meet at least your roommate and try to gauge whether or not you'll get along because they've got the potential to become your best friend or your worst enemy. If you like your quiet, make sure not to choose a party house like mine!
If living in close quarters with a complete stranger sounds a bit daunting, then it might be a better idea to try and meet a roommate in a backpacker's hostel before making the move into a house. Empty twin rooms seem easier to come by than one single bed in a twin room, so it might save some house hunting hassle in the end as well. If you've got a good job or don't want a roomy then there are plenty of single rooms about, but they'll cost you.
You'll also want to consider the size of the house you're moving into. I lived in a party place with 14 residents and usually at least two dossers, so there was always something going on and things were lively. Large sharehouses tend to attract party types so you'll have to be sure you're up for some crazy times and won't get pissed off if people are loud on a Thursday night after a session at the Redback. Choosing a house with just a few people will have its benefits, but you'll have to make sure you get on wih everyone or you might risk feeling isolated.
MONEY & COSTS