How to deal with roundabouts - which lane for straight ahead?
The general rule is keep left unless you are turning right, unless road markings tell you differently, or you are overtaking. If there are no road markings to contradict, then the following applies:
2nd exit, but not as far around as straight ahead; or a straight ahead exit:
If it is a 2-lane approach then don't indicator initially, keep left, and indicate left to exit after passing the exit prior to the one you want.
When there is a 3 lane entrance to the roundabout the left lane is usually left turn only (photo below).
This may be defined by road markings, but may not. If there are no road markings look at the roundabout itself. If there are three lanes on the approach and there are only two lanes in the roundabout, then the left lane must be left turn only.
But if there are three lanes on the approach and there are three lanes in the roundabout, then you should be able to use the left lane to go straight ahead .