I think I'm getting better at this switching between lives. OK so after work I did attempt to pick up the kids from HE friends in a professional- mum-with-efficient-agenda sort of way, and this didn't actually pan out since I was quickly over-ruled and we all went to the park, HE style, ie: with no regard for the time of day, for bankrolling of the kiddie variety.
I do see, from what I've just said, that it might not look so good but the thing is, I took it much better than last time - which was the occasion when I started shouting about raspberries in library books fairly soon after I walked through the front door.
This was a first day in a kind of work that is entirely new to me. It dawned on me rather quickly that I haven't done work with which I am not mostly familiar for at least a decade. It's quite likely that it is useful to be reminded how it feels to learn a ton of new stuff very rapidly. It most reminded me of my first driving lesson: the same intensity of learning a bundle of individually straight-forward skills which somehow become highly complex because you have to put them all together in rapid succession, straight away, without making any mistakes and without killing anyone. I suppose it would have been quite hard to actually kill anybody doing what I was doing today, but the stakes felt high.
Not so incidentally, thanks so much to the person who helped me out. Honestly, I'm really not a complete klutz, I swear. Please give me another chance!