Before proceeding further, it has to be mentioned that listening to Airband Transmissions in the UK is generally illegal, but you can read the sticky note on this forum for the details. Now we have that clear...
I suggest you check the amateur radio websites. The Radio Society of Great Britain (RSGB) has links to useful information.
The dongles intended for digital TV reception can be repurposed as wideband receivers by downloading a couple of computer programs, one to operate the dongle, one to act as an on screen tuner to select the frequency and receiver mode required. The dongles are wide open in terms of frequencies they can receive. Strong local stations can wipe out more distant weaker signals even though the frequencies being received are relatively far apart.
For airband reception, interference from pagers and FM broadcast stations are the biggest bug bear. For best reception, you need to make up a filter to match the frequencies you want to listen to. This blocks the unwanted signals between the aerial and your receiver dongle. These filters can be made with a small coil of enamelled copper wire and a couple of capacitors. All stuff that can be bought cheaply at Maplins.
There is a bit of a steep learning curve, but there is plenty of information on the Internet and YouTube videos showing you what to do. The dongles work very well indeed for the money and are a very good and cheap way to dip your toe in the water to see if you want to consider a more sophisticated purpose built receiver. Dedicated airband and wider frequency handheld and desktop scanners are available from £60 or so, but the satisfaction and experience gained from getting one of these dongles working well is priceless.
You may see some commercially available dongles that claim to be dedicated for airband or other frequencies. Most of these are just repackaged RTL-SDR dongles with a filter built in and software included, all sold at a hugely inflated mark up. There are some exceptions such as a dongles sold for receiving Cube Sat transmissions, but they are few and far between.
Another advantage of computer based systems is that they can be left unattended and software used to record transmissions of interest for review later. Avoids all that listening to nothing but static!
So long as you do not communicate anything heard to any third party or make use of the information for any nefarious purpose, no one is any the wiser. Google searches will reveal a wealth of information which initially seems overwhelming, but you will soon learn that there are two or three main products that work well for most people.