The Home Office has issued revised Guidance on the use of covert surveillance or human intelligence sources by public authorities under part 2 of the Regulation of Investigatory Powers Act (RIPA) 2000.
The codes of practice also provide guidance on entry or interference with property or wireless telegraphy by public authorities under section 5 of the Intelligence Services Act 1994 or part 3 of the Police Act 1997.
The link to the documents is here.