Core: Leaving the roundabout: looking, signalling, priority

If you want to leave a roundabout, you must give way to traffic that keeps following the roundabout (Book p.85). That duty is not limited to cars: it applies equally to (moped) cyclists riding on a cycle lane or path that is part of the roundabout (Book p.85-86). The book itself states a counter-case: if the cycle or moped path lies far enough from the roundabout that it no longer counts as part of it, you do not need to give way to cyclists on that path when exiting — the ordinary rules for that junction apply instead (Book p.86). When exiting there is a separate duty on top of that: before turning off you signal to the right — even when it is quiet, because it is not automatic. The book also advises moving to the right already on the approach road (Book p.83); that is sensible, but not a legal duty: just before and on a roundabout you may also drive other than on the right.