The Radio and Telegraphy Act, also known as the Wireless Telegraphy Act, is the primary legislation governing the use of radio spectrum and radio equipment in the UK. It's managed by
Ofcom,
From Ofcom
Generally, the use of radio receivers is exempt from requiring a licence.
Typically, receivers and scanners can only be used for ‘general reception’ such as licensed broadcasting stations and hobby radio
You don't actually need a radio.
HamSphere:
This is a virtual amateur radio transceiver that allows you to connect with ham radio operators and enthusiasts worldwide, even without a license.
You don't need a licence to listen to Radio either, including bbc radio which the likes of some walkie-talkies have the capability of covering.
An Act to consolidate enactments about wireless telegraphy.
www.legislation.gov.uk
It doesn't say you can't listen
(a)he uses wireless telegraphy apparatus with intent to obtain information as to the contents, sender or addressee of a message (whether sent by means of wireless telegraphy or not) of which neither he nor a person on whose behalf he is acting is an intended recipient, or
(b)he discloses information as to the contents, sender or addressee of such a message.
(2)A person commits an offence under this section consisting in the disclosure of information only if the information disclosed by him is information that would not have come to his knowledge but for the use of wireless telegraphy apparatus by him or by another person.