"It is a crime to use any apparatus, including jammers, for the purposes of deliberately interfering with wireless telegraphy (radio communications) in the UK. The maximum penalty is two years’ imprisonment and/or an unlimited fine. See section 68 of the Wireless Telegraphy Act 2006."
See https://www.ofcom.org.uk/spectrum/interference-enforcement/s... for example
"It is a crime to use any apparatus, including jammers, for the purposes of deliberately interfering with wireless telegraphy (radio communications) in the UK. The maximum penalty is two years’ imprisonment and/or an unlimited fine. See section 68 of the Wireless Telegraphy Act 2006."
Ofcom is the UK's communications regulator.