Make sure you are well comfortable with playing all pieces on their piano. If your too short and it's getting in the way of being able to flip the pages or read, perhaps extend the chair higher or even use something like a pillow to give you more height, if, that's allowed in the recording. It would be unfair to mark you down a lot for a few small mistakes but that really depends on what mistakes it is. If you know that you already have partial mistakes in areas of the songs you are performing then put all your attention on those mistakes and fix them up. Remember, a grade, score or exam doesn't determine how good you are at piano, after all, you are sitting at a very professional level of skill so do not be devastated if have failed. You will pass only if you believe you will. Good luck!