How to deal with roundabouts - sometimes local procedures apply.
The problem is finding out what they are. Within a driving test area the local driving examiners will agree between themselves as to how a particular roundabout should be done.
With this layout (below) the one o'clock exit can be taken as a straight ahead in the left-hand lane. This is allowable, and safe, because it is the 2nd exit.
However in some situations this could also be described as the 2nd exit to the right, and done in the right-hand lane.
However if the one o'clock exit was the 3rd exit, then you would need to do it differently. To be safe you would need to do this exit as a right turn in the right-hand lane (below).
This is because by the time you are passing the second exit someone (that you couldn't see when you initially pulled out) could have come around the roundabout quickly and be on your right hand side. They might then be trying to ram you as they head for the 2nd exit, which is on your left. It is nearly always best, if you are in any doubt, to use the right hand lane to take any turn that is located to the right of straight ahead.