Hi Nick,
Open the 'Page Thumbnails' to the left of the open PDF file.
Right-click in the first thumbnail and select 'Number Pages…'
In the dialog box click on 'Selected' under 'Pages' and choose '1' To: '2' of '33'
Specify the numbering style as 'i, ii, iii…' and click OK.
Acrobat should renumber the first two pages as 'i' and 'ii' and renumber the following ones from 1 to 31.
Hope this helps.