Good luck and if you find youself in the wrong lane for a turning, don't make a late lane change, take the safe option.
they can't fail you for going the wrong way (but don't keep doing it) you will only get a minor for bad planning.
If you think you've made a mistake forget about it and carry on with your ride, you can't change it and the last bit of advice, turn your phone off and go to the toilet before your name is called, the last thing your need is someone phoning you to wish you good luck or busting for a wee halfway though your test.