I spent yesterday clearing out the garage, moving some shelves around and shifting the 'stockpile' around. Then I made a list and put together a supermarket delivery for things that are missing.
When it's finished, there is nothing else I can do to protect my family in the face of no deal chaos. I can still do other stuff like leaflet, write to my MP and so on, but that has less impact on my mental health than knowing that we'll be 'alright' for a couple of months and will be able to ride out the immediate mess.
So, I'm not really that stressed out personally. I'm fucking angry that the government, of a democratically developed country has made me do this, and made me anxious for so long, but that's different to feeling stressed out.
I did this in March too, and the stockpile did brilliantly - we spent £10 on groceries a week for about 6 weeks - bread, milk, eggs and a few crunchy green veg. If there isn't chaos, then it's another load of cheap weeks ahead, if there is, then I've done the best I can.