The medicals are very strict and it really isn't worth hiding a medical condition as its up to £1000 fine if found out.
I myself hold both pcv and hgv licence and due to a medical condition havnt worked since August, during which time i have had tests, trials and had to fill in medical forms for the dvla to notify them.
In turn the dvla have okayed me to drive on the consultants say so.
He is now confident im fit to drive so im back next week.
having a professional licence isn't by any means straight forward and medical conditions are looked upon very strictly, stagecoach who i have in the past worked for have a company medical as well as the dvla one, and in some places bmi is part of the medical.
For the record im 30 years old.