From that Guardian article linked to above:
"In Cambridge, Diane says she is also stockpiling, though she doesn’t want to go into too much detail. “I’m a bit cautious about being presented as an idiot who has a cupboard full of stuff,” she says. She’s OK about using her surname, though: she is Diane Coyle, OBE, FACSS, the economist, Bennett professor of public policy at the University of Cambridge, former adviser to the Treasury, vice-chair of the BBC Trust, member of the Competition Commission, winner of the Indigo prize … in short, really not an idiot.
“The point about supply chains,” she explains, “is that the things you buy in the supermarket today were on the road last night. Supermarkets now don’t have warehouses full of stuff. If we have a no deal and the delays go up even by 12 hours – although I see there’s a new report saying it is going to be much more – then things will stop being put on the shelves. They will run out. And it’s not just stuff we buy from the EU, and it’s not just fresh produce – it’s quite a lot of things.”"
Really frightening. I had the threat of food shortages growing up in Kenya and South Africa, DH experienced them in the USSR and Russia - he remembers his mum bursting into tears at home because bread had run out before they got to the front of the shop queue. I cannot imagine what that feels like when you have little ones at home.
I've today finished(ish) gathering a week's supply of food, mainly following bellini's advice. Thanks bellini 
. I've taken my time to buy things that we'll eat anyway, without breaking the bank too much - lots of lentils, curry powder, tinned veg, porridge, coffee, sugar, jam, crackers, pasta, sauce...