You could specialise in gas safety records/certificates. There are companies who only do those. You could easily go about on an E-bike. In fact that might be the best way to get around, in some areas!
You would inevitably meet the challenge of the country's Estate Agents - unqualified self important people who will try to tell you your job.
What about when there’s gas fires, bbu’s etc. I agree some do specialise in cp12’s but you still need a lot of equipment to do some.
I think the OP would be a lot better off with a job.
