Blood on the streets

Foreign trucks go in and out of ferry ports. Fine them (or confiscate their vehicle) at that point. Educate them on the ferries coming in.

We're an island, it's not like we have porous borders and no way to intercept all foreign HGVs fairly efficiently.

And this idea that foreign drivers don't know the UK rules... how many of the incidents are attributable to foreign vehicles? From what I can see, most are domestic.

Which would never happen, and that's kind of my point- what you are talking about doing, because it only applies domestically would distort the market- if it's significantly more onerous for UK trucks to come into London then jobs will be bid for by foreign registered companies which don't have to jump through all the hoops.

Because it doesn't tackle the issue (vehicles which are unsafe by design to be driven safely in high density traffic, being driven in high density traffic) your solution just changes the flavour of the problem, it doesn't solve it.