The single rule that governs every roundabout is straightforward: give way to traffic already circulating, which means anything coming from your right. Before you commit, look right and ahead. If a vehicle is approaching from your right, hold back. If the way is clear, proceed without dawdling.
Your approach speed matters. Slow down early enough that you can read the road signs, lane markings, and the flow of vehicles already on the roundabout. Rushing the approach leaves you with split-second decisions and poor lane choices.
Lane selection depends on where you are leaving. For the first exit left, keep left and signal left as you approach. For straight ahead, usually stay in the left lane unless road markings tell you otherwise, and do not signal on the approach. For right turns or full circuits, move to the right lane and signal right early.
As you pass the exit before the one you want, signal left. This tells everyone (the examiner included) where you are heading. Stay disciplined in your lane. If you drift across markings or change lanes without reason, you will be marked. If you realise you are in the wrong lane, stay in it and circle round again. Never cut across traffic to reach your exit.