About Merging and exiting: 2/3 of the lane and the 300-metre rule: which statement is WRONG?
For exiting you simply signal 'in good time'; the book does not name an exact distance for the start of the exit lane.
At a too-short merge lane you stop at the START of the lane, not halfway, and only pull away once you see a gap approaching in your left mirror.
Always use about 2/3 of the merge lane to get up to speed, even if you could merge earlier.
You must give way to through traffic; some drivers move left to give room, but that is not obligatory, so do not count on it.
Explanation
trap: a vague 'in good time' assumed where the book gives a concrete number. Book p.151 - signal at approximately 300 metres before the start of the exit lane, using the green hectometre markers as an aid