guiding adult children (adultish at 20)

[oldernotwiser59]

Fruit of my loins on motor bike clipped the wing mirrors of several cars in a traffic queue when driving to work this morning. In a panic (a) about being late (b) scared, he drove on without stopping. Extent of damage (if any) actually not know. He now wants advice on what he should do. I've told him that law requires him to report the accident although if there was no damage I guess that doesn't apply. So the question is, how hard to push for him to do the right thing?

And the legal questions
(1) does reporting now (within 24 hours) absolve him from not having stopped in the first place?
(2) is the queue hopping likely to be seen as careless or dangerous or without due care and attention (not sure of current legal terms)