It would seem fairly elementary, but it isn't! If you want the Page Footer to only appear on the last page you have to set the elements in the Footer to Visible=False and then trigger Visible=True on the last page.
If you have something like an Invoice on the Invoice Footer section you set the Page Footer elements Visible=True.
Its sounds a bit daft but the Page Footer does not seem to be able to accept Visible=False
Simon