My AERO Plus 8 would not pass at all, the silencers and sump plate are all less than 8cm.
It seems that the Belgian MOT people are retrospectively applying modern regulations: all new cars must clear 10cm.
But so far it is not part of the UK MOT.
My road has a primary School, so is a 20mph zone, with speeds humps all the way along. I don't think I'd get in and out with 8cm!
Because the low point on the Plus 8 is behind the front wheels as the wheels lift they raise the sump. Most of the time the sump doesn't contact. Around here the speed bumps are "pillows" and I drive over with one wheel on the pillow, one on the road, which also helps.
For "fun" I went into the garage and re-measured....
Silencer - 10cm
Sump - 8cm. But the Woolf protector adds 1cm, so 9cm.
These are with the car empty...