Rules change while you are turning, or once you have turned
If a car comes up behind, don’t wave them by, and in any case you are bound in law to give way to it. Sometimes the car will stop well short. It has then given up its right of way and you should proceed, keeping an eye on it in case it moves forward or comes round you as you progress. If it comes right up to you to start with or at any time, you must pull forward to the starting position, and begin again. This would require putting on a seatbelt again if you had removed it.
Musn’t give signals to other road users? Quite right in most circumstances, especially pedestrians. The turn in the road is supposed to be different though. However, some Senior examiners do not see it this way and may penalise this, and require their examiners to do the same. It should be the same at all Centres, but I am sorry to say this happens. Be guided by your instructor in this, he knows the Test Centre.