I think roundabouts are one of the most common fears for those of us who are not used to dealing with them. I know someone earlier in this thread failed because of one incident on a roundabout while all else was fine, and this happened to me too. My driving instructor even told me afterwards that it was because I was reading this thread too much and fixating on roundabouts that I convinced myself "we" (meaning anyone who learned to drive in the US!) "can't do roundabouts!"
The thing that really pisses me off is that following my fail, I continued to drive by myself and in fact happened to find myself needing to negotiate three major roundabouts on my route back and forth to a new location I was dealing with. They are doozies, large, busy, just like the one I failed my test on, yet I very quickly managed to deal with them just fine, every single time. However, I was choosing the starting lane I wanted to choose, rather than the one my driving instructor told me to. He had me starting in a right hand lane, then having to jump two lanes to the outside left lane to make my eventual turn.
When I was on my own, I just started in the left or middle lane, stayed in it all the way around, and then just slipped into my exit without having to do this dangerous left-ways lane hopping that I feel is more hazardous than just going all the way around together in one lane. It worked every time when I drove by myself and made my own decisions. I think if I had chosen on my test to do it "my" way, I might have had a minor markdown for questionable lane choice but I would not have received my major fault markdown for screwing up on the "hopping"....