I really, really hope the government isn't stupid enough, irresponsible enough, to settle for a no-deal Brexit,
or to faff around until we end up with that as the automatic default Brexit.
I hope they are just trying to bluff the EU with all this no-deal talk and UK goverment prepping for it.
BUT for those Leavers who want no-deal and claim that many countries outside the EU trade on WTO terms:
In the event of no-deal / WTO Brexit,
the UK would be the ONLY country in the world trading on pure WTO terms
so it would incur punitive tariffs and - even worse - extensive non-tariff barriers, e.g. detailed customs checks
Hence log-jammed ports and delayed UK exports - to all countries, not just the EU
Mauritania (with GDP only 0.2% of the UK's GDP), which previously did trade only under WTO, has recently signed 20 preferential trade agreements
Dropping out of the EU with no deal automatically means dropping out of international recognition for UK certification checks on our manufactured goods, components, food, even airports, airplanes, ships, pilots, captains, crew ...
Hence UK airports, flights, ships and ports would also be stopped until the Uk negotiates an international emergency fix.
Of course, public fury would force the UK government into an emergency deal asap after a no-deal Brexit
However, best case is a few days chaos; worst case is that it might take weeks and a change of government first.