AOA do produce a guide. It issued at every course at MAN. Your problem is that this is driven ,as most airside driving courses are, by a mixture of CAP 642 in the main, with a little of CAP 168 in the mix for good measure. For the application you are looking at neither of these documnets will mean very much.
It seems that every airport runs some sort of course for training airside drivers, and I am sure that most here will agree with me that it is nothing more than following a few simple safety rules, and applying copious amounts of common sense.
On that basis, as there would not appear to be any legal framwork that you have to adhere to, then why not write your own around those simple principals??