I want to have my room in a London theme?

Okay so here is the deal: For my birthday I just want to get my room redone. My budget is probably around 300 dollars or 400 tops. At first I wanted mainly to have my ceiling covered (neatly and professionaly), like Bob Marley, Wiz Khalifa, Scarface, pictures of London, NY city, and things like that. And then to get a mini fridge, some speakers, a new like glass desk, a cheap standing lamp, and some salt lamps. That's really all that I wanted. And some new curtains and bed sheets and things like that. Well, now I think I want my room re-done in a London theme. I love the red buses, and the modern city part. Things like that. Or I might do my room done in a theme of places around the world, like NY city, San Fran, Paris, Tokyo, and London. But I really like the London idea the most. So what are some ideas for my room to make it more themed like London or places around the world?

I know this question may sound really weird and confusing, but I don't really know how to get my ideas down right. Lol,

Thanks.