Perf is not a huge subject to learn, can be tricky at time's but if you have half a brain you should be able to digest it all. Dont be dependant on the feedback to get you through, this can backfire on you as many have found out. Use the feedback as consolidation as you go through your manual.
If i can pass perf first time round then i am sure you can too, all the best for your exam..... the most important formula you need is RTFQ (squared)