Young bloke moving to London

Hi, I'm planning on coming over in the next 6 months with two mates to do a two year working visa.

I'm 22, and want to work (but not full time) and be able to travel to Paris, Amsterdam and the festivals every month or two for a week or so.

Plan to get work through an agency, or do pub work. Not too fussed. Also seen a few recommendations here in regards to best places to live.. I would be more interested in the night life, busier side of things. 

It seems as though living close to central London is extremely expensive.  In terms of living in Melbourne, there are are heaps of great spots around the city centre such as Brunswick St in North Fitzroy and Chapel Street in Prahran.  Something like that would be ideal in London..

Any advice would be greatly appreciated.

It may help to ask specific questions so people can try to help you...

Also, you need to define what is "expensive" to you if you are asking for help to identify an affordable neighbourhood.