I was just downloading a game earlier today and, sad git that I am, read the whole terms and conditions before clicking Accept. There was a lot in there about if you're in the US, this law applies, whilst if you're in the EU, that law applies. If you're in neither, it said in not quite so many words, you're on yer own matey. And it occurred to me, when we're not in the EU all these licence agreements will have to be covered separately by UK law as well, or won't be covered at all. Just one more thing that needs doing that we don't have the time or manpower to do in ONE FUCKING MONTH. Brexit doesn't have to be the end of civilisation as we know it, but they sure aren't going about it in a way that will maximise success.
Re the Y2K comparison, it's almost the opposite actually. There was all the whipped up panic in the papers about planes falling out of the sky etc, which did not in the end happen due, as you say, to excellent forward planning. But in the present day, most of the papers seem to be keen to reassure us there will be no problem come March 29th. We don't need a plan, we just need freedom, it will all be fine... However, if May were to have a sudden brainstorm and actually do the sensible thing, i.e. postpone leaving for a couple of years until things were properly worked out, there would be much fury and calls for revolution. The Will of the People (how I loathe that phrase) is being arrogantly thwarted, and all that jazz.