My girlfriend and I plan to move to the UK (London) for (at least) some years. As an university graduate I expect to earn about 20,000 - 25,000 pounds p.a. initially, my girlfriend expects to earn 15,000 - 20,000 pounds.

Is this enough live on in London? How much money does a couple on average need to cover all living expenses in London? How much should we earn at least ?