Listening to ATC in the UK is illegal.
It's also tolerated as any Police conversation in three decades of doing so has proven.
Scanners are happily sold at airshows, some of the older generation just don't accept it's a harmless and enjoyable past time enjoyed by many. Indeed there's a lot of UK published books on the subject matter, but as Bren says, illegal in the UK #secretsquirrel
With fr24 now being a thing, I can't see HMG getting upset and cracking down, we have more pressing issues of state methinks.