Companion

You don't have to drive alone when you sit your practical test.  Anyone over 16 can (usually) join you.  They can't take part in the test, and should sit behind you, still and quiet.

That person—especially if they're your instructor—could :​

1. Give moral support by being there
2. Explain the result of the test (the examiner will have very limited time at the end)
3. Help open the bonnet (to answer a safety question at the start)
4. Change a lightbulb during the test
5. ​Bring the car back (if the test has to stop before returning to the test centre)
6. See you perform under pressure (to suggest ways to improve)