In order to operate radio equipment as a Radio Amateur in the UK you are required to hold a licence issued by OFCOM.
Licences are available to individuals who have demonstrated their knowledge of radio theory, practical matters and personal/public safety.
There are three progressive levels commencing with Foundation which offers access to most frequencies used by radio amateurs in the UK but with limited transmit power (10watts) and restrictions on equipment used.
The intermediate licence builds and expands on the knowledge and practical experience gained for the Foundation licence and in return offers greater power (50watts) and fewer restrictions.
The Full licence again builds on the Intermediate level with more in-depth theory and practical knowledge and gives access to more privileges a wider range of frequencies and greater power.