Hey inversnecky , I have a Testo 330 but no use for va starter but I defo favour Testo, re your work , don't worry youll be fine, the most important advise I can give in business is always do a tidy job , be nice and curtious and on time with your jobs , word of mouth in a place like Inverness or any place for that matter is priceless ,,, Break downs etc always remember you have manufacturers technical help lines and knowledge comes with time and experience as we all started similar, the company I served my time with in Buckie had me fitting kitchens for years then I went offshore and when I got payed off from the rigs 10 years ago I started up on my own and believe me I've learned more on my own than I ever did, use the forums, Facebook groups even YouTube especially if your not sure in multimeters or electrics etc and if your really stuck then I'm sure anyone here would be happy to help, good luck