Colin,
If the text is in placeholders you can use the last item in the send to list
'only outline'. That will give you the text that is in placeholders not in
textboxes you made yourself. If you do the 'send to' two times, first with
the slides images (you get a table). Select that table and convert it to
text, using Table - Convert - table to text. Do the 'send to' a second time
using the 'only outline', cut and paste your text to the first document.
Other than that, I see no possibilities. But maybe someone else will be able
to help you.