Well done on getting the nav section out of the way!
As for the rest of it, just remember that the examiner isn't expecting a perfect flight. Mistakes won't necessarily fail you, but he will be expecting you to pick up on errors and correct them. I found it helped to talk through every action I made, including instrument scan.
I found it very useful in spotting any deviations from heading / altitude / airspeed and, just as importantly, letting the examiner know I'd spotted them.
Good luck with the rest of it!
