When looking for some advice before driving a left-hand drive car in Europe. A friend of mine gave me a simple tip. As long as you (the driver) are the one nearest to the middle of the road, then you're okay. So, I suppose in your case you just need to remember that as long as you're the one nearest the side of the road then you're okay. It worked for me.

As long as there's other traffic on the road you won't have a problem with roundabouts, I was worried too, but it's completely intuitive once you're faced with one.