Hello again Macropod!
Yes, having checked the guide you are indeed the author, I originally downloaded it for a very simple date query in 2008, but this more advanced problem has been on my backburner since 2012....
I've tried the attachment you supplied but with mixed/limited results. On first run using todays date (11/12/2014) it worked, but with any subsequent changes to the issue date box the fields do not update, and on one occassion all reverted to the same date.
I have tried to study the field codes in the document, and whilst they make a little more sense, not enough for me to know what to do

and this does need to be 'user proof'
The final thing was that in Point D in the document there are actually three date calculations needed. The first and second are the between Monday to Friday calculations, which if 11/12/2014 was the issue date the answer would be Monday 26/01/2014 to Friday 3001/2014. The third calculation is the Monday 12 weeks after the date of issue, so if issued 11/12/2014 the answer should be Monday 02/03/2015
My apologies that I did not make that clearer in my original post.
Ballst