The HSE have published a guidance book on the Diving at Work Regulations 1997 for recreational diving projects.

HSE Approved Code of Practice
HSE Approved Code of Practice
This Approved Code of Practice is one of five Codes that give advice on meeting the Diving at Work Regulations 1997. The Code applies to divers who are engaged in recreational diving projects.
Among the areas covered are: responsibilities of clients, contractors, supervisors and divers; project plans and risk assessment; diving teams and working practices; diving plant and its maintenance; medical checks.

The Code of Practice applies to projects where at least one person is employed or self-employed and engaged in work and recreational divers and the purpose of the project is recreational diving, that is diving carried out by a person for recreational purposes while not at work.

The Code of Practice  covers  instruction and being a dive guide, underwater journalists, stills photography.
A free downloadable copy is available from the HSE Recreational Diving – Approved Code of Practice.