Accidents have also been caused by motorists in the left lane going straight ahead..

As you approach a roundabout, if you want to take a left, U-turn or go straight, stay only in the left lane,

Roundabouts work if you do 1 lane change per exit you pass, but that requires people follow the road markings.
And that there are road markings.

I think we're abandoning roundabouts in favour of overpasses and sliproads - these will work better here.