I hope your planning is well underway. You haven’t had much time but you will have the chance to develop your skills especially for your speaking exam. You can see a tape of sections of the South China Morning Post final debate from earlier this year (only one side of the case!) : http://www.youtube.com/watch?v=jhhwk0rOQtg. These students have had more time to research their topic and prepare their speeches. You may still get some ideas about using evidence and how to present your case.