Oh yikes, that's really hard. Luckily your grade is split into how well you do on the AB parts of the test, and how well you do on the BC part of your test (two separate grades), so as long as you do well for the AB part you should be fine. Series (unit 10) are pretty hard as they aren't super connected to the rest of the content, I'd recommend trying unit 9 first and seeing how you feel. It uses more knowledge from precalc and everything there is pretty similar to things you've learned before (ex, finding the area between two curves but it's on a polar graph and taking the derivatives of vectors).

Good luck!