Yea, the roundabout I was on today was on a dual carriageway (although a 50mph stretch of dual carriageway). I was coming off a residential street that joins the dual carriageway via this roundabout - left or right depending on which way you wan to go. The cars already on the dual carriageway and continuing along it were coming along from the entrance directly to my right at speed giving me little chance to get on.
So you were failed for it? This is so frustrating, I'm confused. I waited a good while looking for 3 empty lanes but there was always someone in the lane closest to the centre of the roundabout when the other two lanes were clear. My instructor ended up getting a bit frustrated saying - 'you've got to go - look, your lane is clear' because in his eyes I'd already missed a chance to go. I'd had a crap lesson as it was so I didn't want to ask what I thought was a stupid question. Maybe it's not that stupid of a question. What are you supposed to do?