Roundabouts are really very logical. Generally, position to take the shortest path through. Here's how to think of them.
The video shows how they work. Also see one about mini-roundabouts and small roundabouts. After that, consider how you'd navigate local big ones. Last, see my fly-through of a spiral roundabout, and get to know "drive-thru" ones !
Here's more about signalling, including the "12-o'clock rule", which concerns when to signal right as you approach.
But don't worry if you feel overloaded navigating complex junctions like these. (A lot of this is about making choices).