This question pops up here frequently. From what I remember from the many previous times this has been asked (as I am in the US), the British government bans listening to ATC frequencies.
At one point last year there was a person sending LiveATC a feed of an airport out of the UK, but the site received a request from the British government to pull the feed. While the site's owner was under no legal obligation to do so, he did do so out of respect for the country's laws.