When joining and leaving make proper use of the acceleration and deceleration lanes. Not to do so could mean your speed is out of sync with the traffic you are either leaving or joining. Take account of the higher speed of the traffic.
Make sure you are practicing your MSM and PSL routines. At the higher speeds the process of taking and giving information becomes more important. Watch out for the lines and signs, they are there to help you. Do all you need to do in good time.
It is not always possible that the examiner will be able to take you on a dual carriageway. At some point they will get you on to a road where the higher limits apply. If there is a sat nav in the car note the speed on that. But be aware that any speed limit shown outside the car will be the one to obey.