How to go about ....life in London ?

Am a single malaysian female age 30 intend to go to London and find job...if lucky enough. In my effort to find job in London, recently received job notification from monster.com and ask me to furnish cv to one of the oil and gas company located in london. Job is not specifed just asking me to forward cv. anyway one of the detail that i need to provide is the expected salary. Problem is that i do not know the cost of living out there. Anyone, please guide me.