BEagle sums it up well. There are many failable items in this test but there is so much scope to demonstrate good airmanship, which will far out weigh the odd mistake here and there. As someone else said, impress the examiner at the start with loads of airmanship and common sense and you are half way there. Remember a PPL is a licence to learn, as you, I and I think all of havn't learnt it all yet and never will.
WE ARE NOT PERFECT!