The following part of the document seems to be on the right lines.....but when i 'toggle field code' i cannot make any sense of what is returned.

"Calculate the day & date of a given day of the week next month

Thursday, 8 December 2011
Note: The value in {SET Weekday 3} determines the day of the week to return (0 = Mon, 1 = Tues, 2 = Wed, 3 = Thurs, 4 = Fri, 5 = Sat, 6 = Sun), while the value in {SET Week 1} allows you to specify the week of the month. The ‘Limit’ variable is used to prevent the chosen date rolling over into the following month. This also means that setting the Week variable to 5 will always return the last instance of a given weekday occurring in a month."