Don't forget the Q&As for your exam...
Read parts of your ATPL notes again and it may give you ideas for your half hour presentation. A/C General and Met are always good subjects to revise as an instructor is expected to have sound knowledge in this area.
I was told that to answer a question from a student you need to know the subject inside and out and the ATPL notes were about the right level to fully answer a PPL question with detail.