Mr. Bitsy, just accept it. You are not supposed to listen to ATC frequencies. At present, and for as long as anyone I know can remember, the relevant authorities do not take action against someone who listens to the frequencies out of interest or other innocent reasons. But it is not a right under the UK legislation as it appears to be interpreted by OFCOM and, I presume, the British courts for the time being.
People who use receivers, and worse, transmitters, on ATC frequencies for nefarious purposes or who create interference on the frequencies are deservedly tracked down by the authorities.
If all you want to do is listen in to improve your skills or whatever, just do it and keep quiet. But accept that it is probably not lawful for you to do so.