I've never done a short course but I believe they were originally designed for trades people like yourself, If you work to a high standard then it may not be too much if a problem. What gets my back up is that lot of training providers abuse the course and mislead the trainees in to believing they are electricians, some people come out with wasted money, some just don't care and start rewiring peoples houses. Its like anything though, some are good, some are bad. Depends on the person.
You mentioned consumer unit upgrades on most of your kitchens......
In my opinion this is where you could become unstuck. If the wiring is old I personally always offer to install new circuits for a kitchen and add an additional CU. Just be aware that changing a Consumer unit make you responsible for everything connected to it so everything needs testing fully before undertaking these works, a dodgy circuit shouldn't be reconnected to a new consumer unit unless its safe, if you change the Consumer unit and then find a problem (missing earth/ tripping RCDs) than legally its down to you to rectify it.. For free !