Great Keith, you are challenging this "dying" trade, if I can express it that way. I' been doing a lot of board repairs, air-conditioning modules, lcd-psu's also got myself into the musical instrument repairs, guitars and amps, I used to build amps in London back in the 60's for Nolan NB (Holloway), also worked at Midas and WEM.
We had the Matsui invasion 1990, locally known as Firstline and Basicline, later Vestel sets 11AKxx under the same brands, the money making era, I worked for Carrefour (contract) and at one time reached 15 calls a day, now I'm lucky if I get 1 call in 15 days.
Haven't looked into cameras or mobile phones yet, feel clumsy on small repairs, may give them a bash.
I'm near retiring age, so the struggle for me will be relatively easy, I worry about the younger people in the trade. I closely work with some locall tv shops, help them out when I can.
Don't now about UK, maybe you can tell me here, work licences are limted here, I can only repair domestic apliances (brown goods), no industrial or profesional products, and no arial rigging or repair, also my licence doesn't allow me to sell anything.

Frank