Work out your P.O.T. (highlighted on diagram) by practising in a quiet car park - most bays are a standard width leaving about one foot each side of your car when parked centrally, although the size may vary, meaning you would need to adjust your point of turn (for example make it earlier for a narrower bay).
What happens on the driving test?
You will normally get the opportunity to reverse into a bay reserved for test candidates in the test centre car park ready for your test. You may be requested to do this exercise at the beginning of the test or on the way back into the test centre after your drive. You will need to position your car where possible ready to reverse into a bay at a 90 degree angle as shown in the diagram. If at any time during the manoeuvre vehicles, pedestrians or cyclists approach, allow them to pass but do not wave them on.
Carrying out the manoeuvre
Pull out from your bay into the starting position shown (if you are carrying out the manoeuvre at the end of the test stop directly in the position shown for starting position).
Prepare - Select reverse gear and find the biting point.
Observation - Check mirrors and out of each window to ensure it is clear before moving. Mainly looking out for pedestrians and oncoming traffic. Remember as it is a car park more pedestrians will be around than normal.
Move - You need your car moving slowly when doing any manoeuvre, so try driving with the car just at or near the biting point to control speed, whilst keeping constant observation (mainly over your left shoulder out of rear window). When you reach your point of turn apply full lock to your left (when reversing into a bay on your left as above) or apply full lock to the right if the bay is on your right.
Keep car moving slowly checking out of your door window as your car swings out as you steer. When you have straightened up (your car should be parallel to lines) look back over your left shoulder out of rear window as you reverse.
It is advisable to open your door after parking to check you are within the lines. If not, then you should pull out and correct it maintaining good observation including out of the back window when reversing back in.