Where you work. Pay differs across the UK. Compare adverts and ask employers in the area you will actually work in, not national figures.
Overtime and call-outs. Some jobs add paid overtime, call-outs or shift work to basic pay, and some do not. Ask how often it happens and how it is paid.
Employed or self-employed. Working for yourself means setting your own prices, but also paying for your own van, tools, insurance, holidays and quiet weeks. Employee figures cannot tell you what would be left.
Where you take the work. The National Careers Service says that with experience you could train as a heat pump engineer, work on ventilation, air-conditioning or renewable heating, move into building services engineering, or train apprentices. We have no official figure for what each of those pays.
Gas work. In Great Britain, everyone who does gas work must be competent, and employers and self-employed gas workers must be on the Gas Safe Register. We do not teach gas work, and we have no official figure for what it adds to pay, so we claim none.