That's similar to how they do it in The States, mate of mine had a collision at an Intersection, Police arrived, weighed the situation up then cited him and issued him with a fine which he had to pay right away. Saves loads of paperwork I guess .
As far as undertaking goes, well, it's allowed in The States, one of the reasons (there are others) why the death rate is 3x the rate here. IMHO, lane discipline is extremely important, It's been a few years since I drove on a really busy Motorway like The M25 but from what I remember it was nothing like driving on The Interstate in Denver with cars, trucks, buses switching lanes randomly, I don't think I've ever been so for such a period of time while driving.
Pete