The FM (VHF) band London is fairly full. It is not impossible to listen to many of the main BBC stations, or Resonance FM and the others, but there is often interference. I have bought two DAB radios and also listen via the Interweb... needs must.
As I walked through Hackney, Queensbridge Road, one dismal night, I listened to many of the pirate stations and legal stations, playing house, hip hop, dance hall etc etc, and I guess a few low power community stations as well. Walking from place to place, I often re-tuned the radio on my mobile phone, when I tired of one of the stations. This process was repeated a few times, so I guess I was picking up the strongest stations as moved around (scanning for strength 5?). If I was in a car or a bus, I would find new stations more quickly, but I like to walk.
If I went North, I would expect find Greek and Turkish language stations, as I went towards Stoke Newington and Green Lanes.
This might be more fun in Tokyo, where there have hundreds of very low power FM stations, which can only be heard with a few blocks, or less. The peak power of transmission is one watt!