It's normal to be afraid, stay calm! I also was with some good years of driving in my country, mostly because of the speed, here is 80-100 in the city comparing with our 55... anyway, just look in the mirrors in the roundabout especially, left-right quick checking, u never know from where is coming a "Speedy Gonzales"
:-)...yeap, mirrors are quite useful here, base on them! And Welcome...to Matrix!!!!