Although in practice, nothing is likely to happen, remember that is is not only illegal to pass on information but it is illegal even to listen to any transmission for which you do not possess an operating licence.
This is mentioned in the extract of the Act in a post above.
And Joe Public generally do not get licences to receive anything other
than "Authorised Broadcast Stations" and the like (which also means that listening to a pirate music station is also an offence).
(But the odd thing is that you can buy and possess such equipment so long as you don't use it!!).
The position seems to be that although it is technically illegal, so long as no harm is done then it is tolerated - but for how long, with all of these Anti-Terrorism rules creeping in?