Best of Luck
If its registered as a campervan rather than a commercial, and its being tested at a normal garage, they'll never get it on a lift (or even inside) so won't be able to have a good look underneath. Its bound to pass, as even if it goes to one of these corrupt b@st@rds in the garage trade, he can hardly sell you a set of pads and a new exhaust.
But do check the lights