Iavas -
Get out in that car with Eru and practice, practice, practice the parallel parking until you can get it just right. As far as the other tensions, unfortunately those driving instructors can sense it, and it will only hurt you. Get past the apprehension, do NOT drink large amounts of coffee or other things that will just make you more nervous, and try to imagine that you are just taking the test as a trial run, with Eru or someone else that does not make you nervous sitting in the seat beside you.
Being a semi-relaxed and confident driver is what they mainly are looking for, someone who knows the rules and the techniques and can just put them into play as they need to be engaged. Be alert, but not tensed up, clutching the wheel and looking around far more than is needed. That indicates panic and uncertainty in your reactions.
Do not rush yourself, but at the same time, try and figure out just why you are so uptight about the tests. Work past the fears, there is nothing else that you can do otherwise.
You will do just fine the next time. You need to convince yourself of that fact before you even go in to take the test. It does work.