An applicant for HGV must have a visual acuity of at least
6/9 in the better eye
6/12 in the other eye
when wearing contacts or glasses if needed.
As long as you can pass they required eyesight test when weasring your glasses it shold not be a problem.
I know more than one driver who is as blind as a bast if they take off their glasses but with the corect prescription glasses they are as capable of driving as anybody else.
It is nonsensical to suggest that you take the test without wearing your glasses. You would not drive without them so why take the test without them?
Take the eyesight test wearing your glasses and see how it goes.