The practical test makes sure you can drive confidently and safely in different road and traffic conditions, and that you know The Highway Code (and can show this by the way you drive). It lasts about 90 minutes.
For about 10 minutes of the test you’ll drive independently: your examiner will ask you to follow signs or give you directions to reach a destination. This is so you can show you’ll be able to drive safely on your own after you’ve passed your test.
You’re allowed to take your instructor with you on your test. It’s useful to have your instructor with you: they can help you work on any problems the examiner notices, either to help you pass next time if you fail the test or to sort out any minor faults. Having someone you know with you can also help you to stay calm during the test.