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!