hey there, im just about to hand in my ext. two on friday, and i did poetry.
theoretically it is fairly free form and you have a considerable amount of freedom, but the limitations are set in order to gain higher marks, as long as you demonstrate an extensive knowledge of poetic concepts and 'accepted' structure, you should be fine.
and you do have to explain why it is formatted like ' whatever' and who your influences are/were, why you changed it and how the process has added to the progression of your works.
but. it is pretty good, i loved it. all my poems are pretty free- formish, and a lot are set out in an 'unconventional' way.
it was a pretty awesome exploration, i would advise taking it.
good luck