Just yesterday I was told of another learner who had failed the driving test in mill hill during rush hour due to a silly mistake coming out of the gate within minutes of starting the practical car test.
The learner and his instructor who were not familiar with the area did not know the procedure about keeping to the left when approaching the automatic car barrier even if turning RIGHT onto the main road. The learner stayed in the middle, and even though nobody tried to enter the car park while he was exiting, still got a serious fault for wrong positioning at a junction.
The reason for the serious fault was the candidate would potentially be holding up traffic if another vehicle was entering the car park, and also for not paying attention, as the examiner ALWAYS advices to stay ON MY SIDE when exiting.
If you want a better chance of passing at Mill Hill test centre, then get in touch, as with over 10 years using this centre and area, I know all the things you need to avoid in order to pass.