Answer:

Every radio transmission is licensed somehow. Almost always it's the device that's licensed. E.g. your phone or CB radio or PMR446. The magic of amateurs is it's us that's licensed so we can make and alter devices.

Transmitting without a licence is an offence. It would be OfCom's duty to investigate and penalties are laid out in the Wireless Telegraphy Act. A pirate would be looking at fines and confiscation of gear.

Their level of motivation is going to depend on what you are interfering with.

On the amateur bands, it's more likely just that nobody would speak to you because it's a violation of our licence to transmit to a non-amateur. Anyone breaking that to talk to you wouldn't be filled with sunshine and rainbows.

Locating transmitters is pretty straight forward and useful to the hobby, both for locating interference and locating hidden beacons in a “foxhunting” game.

There's an exception for emergencies. If someone's life is at risk then all bets are off and you can crack on, but 999 should still be your first port of call if available.

If you just want to have a shot you can be supervised by any amateur to operate a radio they have permission to use under the terms of their licence. You could check in with a nearby radio club to see it that is something they could entertain. Alternatively you could go and buy a pmr446 radio or a CB radio. Neither need you to have a licence.

PMR446 is very local so results are going to vary depending on where you are. Ringway Manchester on YouTube is promoting regular PMR446 nets which are getting good results so there might be more traffic than you'd expect and if you can get up high they can have quite significant range.

I've had a shot. I got another amateur once and someone at work who was polite but clearly didn't want me on “their channel”. Any amount of listening will turn up kids with toys and restaurants.

CB is similar but a bit more power and a bit more likely to catch atmospheric conditions for long range DX contacts. The long hot summer this year saw contacts the length of the country. More populated with people happy to have a chat.