my sympathy pal i was nervous as hell before my tests and luckily i never messed up, i knew that if i had tho that`d be the end and i would dwell on it and from then on keep making more even silly mistakes. as i was told by rog i think (great advice) if you make a mistake forget it and carry on it may only be a minor and then you go screw test up doing a serious not concentrating, all over nothing. i also got told to eat a bannana 20-30 mins before test as it contains potassium and supposed to calm you down, worked for me.
best of luck on 8th seems like your ready just need to keep your cool.