Hi loose Cannon,
I haven't looked at the Handbook for a while. But I think the issue is that a pre-board check has to be carried out, but if there is no evidence to look at other than, for example, a sick note from your GP and/or your ESA50, then that is the only evidence that will be considered.
So if the evidence doesn't indicate that you may be terminally ill or exempt then the pre-board check will is likely to be a very perfunctory affair.
Good luck,
Steve
Nothing on this board constitutes legal advice - always consult a professional about specific problems