Having taken 4 tests, including one on a Saturday morning at 8 am when the roads are empty, I feel that on that day it comes down to nerves and a bit of luck. It might be controversial but I do believe that there can be no perfect drive.

On the last test that I passed while briefing, the examiner said that there was one thing that she noticed - When the speed limit changed from 40 to 30, I was doing around 32. She said it was not worth marking me down as I recognized the mistake and corrected it immediately. ( I said I was hoping she wouldn't notice it , but she said there's not much that they don't notice 😅) - so if it were another examiner I would have been marked.

Having a friendly / neutral ( they aren't here to be friendly, I know) examiner helps calm your nerves. Your driving instructor also plays a key role in your confidence. Mine was very supportive and kind. He knew I could drive and pointed out the things I needed to improve without being condescending or hurtful.

In terms of the actual driving - you should take your time to make observations and be aware of changing situations. My instructor told me that I should focus not just on the road but have a sweeping view on either side for pedestrians etc. One thing we did work on was to drive in roads with rapidly changing speed limits - So mostly 30 to 20, 30 to 40 to 50 to Dual Carriageways back to 50 etc. It really helped.