Wireless microphones and in-ear monitors in the UK are generally available at VHF (170 - 210 MHz) and UHF (470 - 790 MHz).
There are three ways in which you can legally use them:
The ranges 173.8 - 175 MHz and 863 - 865 MHz and 2400 - 2483.5 MHz can be used without a Licence subject to the requirements of The Wireless Telegraphy (Exemption) (Amendment) Regulations 2006. These ranges are also used by other low power equipment so can be subject to interference.
UHF shared frequencies can be used anywhere in the UK once licensed. The licence can also cover anyone hiring from the licensee. Frequencies on this licence are provided on a non-protected basis as they could be shared with other users in the local area. Ofcom PMSE team does not coordinate the use of these frequencies.
Co-ordinated frequencies are licensed at a specific site for short or long term. They provide the best protection against interference from other licensees, and are planned to avoid interference from television transmissions.