What sort of place are you used to? If you were brought up in Manchester, coming to London to live won't be quite so much of a shock as if you are accustomed to a village.
Travel in London is deceptive. Some places look close to the centre and are but getting to and from them takes ages; it took me longer to get from Westminster to a place in Wood Green, in North London, near Tottenham, than it did to get to Luton. Ideally, you'll be close to a tube station which is on the same line as your place of work, or on an overground one which takes you directly to close to it. The tfl.gov.uk site is a great help in routes and timings, as is the trainline.com for train routes and times.
And get an A to Z of London.
Otherwise it's a bit hard to advise more, without knowing where you'll be required to work