Don't sweat it. You'll pass or fail completely regardless of how well you drive, unless you do something illegal, like no seat belt, speeding, or crashing into something.
But if people consider you to be a decent or good driver that's all you can really do. You'll try your best and if the instructor is in a good mood you'll be alright.
I got my licence 18 years ago, before I took my practical I could drive quite well, better than a lot of adults. I could easily run over a tin can with any tire you wanted, I could "stunt" the car, I had pretty reasonable control.
I failed my exam. The instructor said that because I didn't have my hands at "10 and 2" and because I shifted while in a turn (I was driving standard) that I didn't have any control of the vehicle.
My friend had one hour of actual driving experience, and he passed. He went on to have multiple accidents.
So, really, if you pass or fail it has very little reflection on you... and I honestly wish there was skill involved so we could get rid of some of these seriously timid drivers that are out there causing accidents.