My future exam

On the eve of the most important english exam in my whole life, I feel all at once exited and stressed...
Exited because one of my biggest dreams is to be able to speak English with perfect fluency, and stressed because it will be an exam based on writing ability. That is to say that I have to build my sentences clearly, without any errors, and at an advanced language level at the same time. This is one of the reasons why the life of an engineer is prone to be difficult. You've understood: that's very hard for me. Since I started learning english, I've always had the same problem: I hardly succeed in making some sentences with a real sense and afterwards, by wanting so much to build beautiful sentences, they become very complicated and finally totally incomprehensible.
Nevertheless, one should bear in mind that in my studies, it's high time my english turned into a clear language. Heck, another challenge for me: settle the problem within my competitive exam !
But.. As for now, I should go to bed !