Well it failed!
Full story is in the blog, but the majority of stuff was very minor, a loose screw here, a missing grommet there. Most important was that he spotted a very small leak in the master cylinder - I will replace that very shortly. There was also an issue with the (MotaLita type) steering wheel which has too many holes and too much wood. Otherwise, side repeaters apparently necessary, and the rear foglamp/reversing light combo needing a shim to make it present the light horizontally on a sloping surface.
What was obvious was that a neatly presented car immediately gets the examiner on your side. I suspect he erred on the generous when assessing seat heights, headrests, two speed wiper speeds, headlamps and quite a lot else. He was very happy to chat and was pleased to see that I obviously had worked through the IVA manual.
So - another month to fix the items, a retest and I should be away.
Thank to you all for your comments and support - it has been incredibly helpful and generous.