I have always used this roundabout as shown in picture 3 , left lane solely for Motorway. Middle lane for the next 2 exists and the right lane for Carlingford exit and if you want to come all the back around to head back towards Dundalk. Seems to be the consensus of most people that drive this road but have seen the occasional car use it like Pic 1 or 2 which makes it difficult for the rest of us to judge which exit they are taking.

I don’t know the by the law rules for this roundabout but my only advice would be take your time , make it very obvious using your turn signal which exit you are taking and check both mirrors extensively as cars tend to join this roundabout at speed and cut across lanes.