@gmayor - thank you. I have located the printer tray numbers - it is more that my document may have (and of course not every letter follows the same pattern...

eg page 1: letterhead, page 2 follow-on (MP tray), //Section Break // page 3: letterhead, page 4: letterhead, page 5: letterhead //Section Break // page 6: blank, page 7: blank //Section Break // page 8: letterhead, page 9 onwards: blank

my limited knowledge of macros does not extend to working around this!