Re reading your original posts I just wonder whether you might not be better off taking a slightly different tack. I don’t know how long you were in the forces nor how many different fitting jobs you have had since, but every one of the ex forces fitters I have worked with in the past has struggled to begin with on civilian vehicles.I am not meaning to be insulting but are you really confident with working on other than Volvo ?
As a qualified electrician with mechanical experience maybe you could consider becoming a mobile diagnostic specialist. You would only need a small van, no HGV driving to worry about and there will be far more demand for your services than in the oversubscribed mobile fitter market. The potential labour rate would be higher as well. Locally to me there is for cars a very successful mobile specialist. He does however have a background as workshop foreman and ‘supertech’, or whatever it is called, with a main dealer. He is in constant demand from individuals, to independent garages, to franchised dealers who also take in other makes.
The downside is the cost of the equipment, which is not quite as good as the dedicated dealer gear, and the need to interpret what is being revealed. There is more to this than just interrogating the ECU, there is some very sophisticated fuel injection diagnostic kit about as well.