You must be regarded as domicilled in the UK. i.e. already living here for a significant time BEFORE you get benefits.
First live here long enough to qualify for them. People who come just to get benefits are NOT welcome and the government is closing down hard on that.
Apply to your local Dept of Work and Pensions. They may refuse applications from persons they consider are not entitled.
turn up without any documents and say 'asylum'
seems to work for many many thousands !
Are you a citizen , legal resident or legal immigrant ? If not , forget it .
