I went on the driving test examiner course a dozen or so years ago, having never been a driving instructor but as a professional driver. They made a big thing out of wanting some non driving instructor intake. I found out that it's terribly paid - despite the acceptable promises I received at the interview - even in the London area, plus it's so regimented as to make it more or less unbearable. All tests are very strictly timed on precisely prescribed routes and if you don't do seven a day you're on the carpet. One of the guys I met there, who happened to be a glider pilot, was so disillusioned with it he went back to being a driving instructor PDQ.
A four week course that was so full of PC and extra stuff that had been added over the decades, it really needed to be eight weeks. The best thing about it was being on the Cardington site.
I ended up doing the FE (PPL) instead, two day course AoC and done.............