I don't know how the system is over there, but I'll share my experiences anyway
In Finland we have to take a certain number of lessons, both theoretical and practical, and first take a theoretical test and then a practical test once the we have passed the first one. I was also extremely nervous for my tests, especially the practical one which I assume is similar to yours - you drive around in normal traffic with an examiner as passenger.
What I think is good to remember is the fact that the exam is not meant to be insanely difficult - it's meant to be just like normal driving. That means that if you actually know how to drive and behave in traffic then you'll pass, and if you fail then there is a reason for it. Granted, with an examiner you are usually much more nervous but (unfortunately?), if you can't drive properly just because of that, then maybe you really aren't qualified to drive?
I did end up passing all of my tests at the first go, even if I made a mistake during the driving part (messed up my parallel parking and did stop a bit late for a car coming when I was turning out to the road). I was sure I was going to fail, but the examiner said that overall I did pretty good so I passed. Once I started driving, I was more concentrated on that than on being nervous, I think you'll be more relaxed as well as soon as you get behind the wheel.
Good luck with your test! (and please tell us how it goes
)