Go to London and find work without agency???

Hello, I am thinking about going to London, check in in a hostel and then try to find a job. Do you think that works/is difficult/a good idea? I am looking for work for approximately 3 month. I am quite a bit worried about how soon its possible to find a job, because I don't have to much savings... Has anyone tried that/has experience with that? Any advices? I don't have much work experience bit I am not picky with the sort of work (I only finished school last year (in Germnany) and have been full-time volunteering in Britain since). Thank you for any sort of advice/tips/experiences. Hoping for positive comments (that it's a good plan ) *please* Felix W