two things I hope you do...you call your MP and have him change the law, and then buy a radio
But we don't need to.
The UK has a long and honourable tradition of common sense, which includes the law enforcement agencies turning a blind eye where a law is widely broken but the consequences are judged to be trivial. Clearly it is considered that simply listening to an airband radio poses no more of a threat to national security here in the UK than it does in the USA.
That tolerance soon disappears, though, if those who indulge in the hobby go out of their way to attract attention. As has already been noted, anyone who puts a live feed of UK ATC traffic on the internet can expect to feel the long arm of the law on their shoulder, which is why you won't find any such feeds.
Yes, of course it's inconsistent application of the law, but over here we find that this kind of commonsense approach works well, in many areas.