Just remember the Examiner will only give you basic instructions such as 'turn the car around using forward and reverse gears please' which is their way of asking u to do a three-point turn. They will only say the instruction ONCE, so you must listen carefully. I failed my first test doing parallel parking as the Examiner thought I was too close to the parked car, and intervened using the brake.
If they intervene in any way, you instantly fail.3 crosses on the sheet and you fail too. But don't worry, just use this time to get extra practise in, and ask your instructor to take you to a good Test Centre. I did my first test in Central London, and it was a nightmare!
Enjoy the test and obey all the road signs

and dont panic
I'm sure you will do well. If you want a good car once you've passed, look on AutoTrader. (www.autotrader.co.uk) Dont get anything under £1k.