I don't know whether to be pleased that the government are finally planning something (albeit a bit late in the day) or horrified that the prospect of a crash-out could actually become reality.
I think it's highly unlikely any government would intentionally crash out but given the total incompetence so far it's not beyond the realms of possibility. And if we do crash out, then yes there will be short-term chaos and people should be prepared for it. If the government are stockpiling food, it could well be rationed out in a crisis.
I think too many people are unaware what "no-deal" actually means:
Falling back on WTO rules mean that we cannot treat goods of EU origin differently to goods that originate anywhere else in the world.
Either EU goods would have to go through customs like goods that originate in other parts of the world - which would mean serious delays as we don't actually have the customs infrastructure in place, hence the disruption to food supplies and the need for stockpiling - or we could just wave the trucks from the EU through, but we would then have to allow goods from anywhere in the world to come through equally uninspected - who knows what might turn up? There would be no guarantees of food standards.
And it's not just food. Just as worrying is medicine, which would be subject to the same customs checks. Even more concerning is cancer-curing drugs which can only be transported from the EU to here if we are part of the Euratom agreement as they are radioactive. We don't produce these drugs here.
Also, all our airline operations currently take place as part of the EU open skies agreement. This covers flights between us and EU member states, but also between us and all the other countries in the world. If we are not part of this, we have to fall back on old legislation which allows for far fewer planes to fly.
As I said, I can't in all honesty believe that any government would be so foolish - they wouldn't be re-elected for a generation if they caused such chaos - but given how little progress has been made so far, it is a possibility.
People can bury their heads in the sand as much as they like, but there are members of the government who are actively seeking a no-deal scenario and it would be chaotic. Just because we have been fortunate enough to live through a very stable few decades, does not mean chaos cannot happen.