Gas Safe –

Gas Safe Register is the official list of gas engineers who are registered to work safely and legally on gas appliances in United Kingdom, Isle of Man and Guernsey.

http://www.gassaferegister.co.uk/

OFTEC -

OFTEC is the Oil Firing Technical Association and is the technical and marketing body for the oil firing industry in the UK and the Republic of Ireland.

www.oftec.org

Association of Plumbing and Heating Contractors -
The APHC is the leading employers trade association for the plumbing and heating industry in England and Wales. 
www.competentpersonsscheme.co.uk

Energy Saving Trust -
The EST is an independent, UK-based organisation focused on promoting action that leads to the reduction of carbon dioxide emissions - a key contributor to man-made climate change.
www.energysavingtrust.org.uk

National Energy Foundation -
The NEF empowers individuals and organisations to take action to reduce their carbon emissions through energy efficiency and use of sustainable energy sources to counter climate change. 
www.nef.org.uk

Health & Safety Executive -
The HSE protects people against risks to health or safety arising out of work activities.
www.hse.gov.uk

Environment Agency - 
Our principal aims are to protect and improve the environment, and to promote sustainable development. We play a central role in delivering the environmental priorities of central government and the Welsh Government through our functions and roles. 

http://www.environment-agency.gov.uk/