There’s this much to be said for Brexit. It is a continuing education about our country and its mutual and intricate dependencies with our closest neighbours. Did you know – I didn’t – that almost half of the human sperm imported by Britain comes from the sturdily productive menfolk of Denmark? This is one of the more fascinating revelations in the first batch of government “guidance” documents about the consequences of a no-deal Brexit. The 24 papers released so far – with 56 more to come – are supposed to illuminate what it would mean were Britain to tumble out of the EU without any agreement about the future relationship.

This exercise was originally demanded by the hard Brexiters when they were all in a clamour for the government to put more effort into planning for no deal and lambasting Theresa May for not overcoming the Treasury’s resistance to spending a lot of money on the exercise. Some of the Brexiters made their demand for these assessments in the belief that it would fortify Mrs May’s bargaining position with Brussels by signalling that she was ready to stomp out if Britain didn’t get what it wanted. Others sought “preparations” for a collapse of the negotiations because they have always willed the talks to fail. They have always been no-dealers. There is not a majority in Britain, not in parliament and not among the voters, for a really hard Brexit, but there is a noisy faction of the Tory party that yearns for precisely that. Most Britons would rather swerve than go off a cliff edge, but the Brextremists want to hammer the accelerator.

Yet there really is no pleasing some people. The government has started to gratify their demand – and now they are angry that they are getting what they say they wanted. Brexiters are heard complaining that the release of these papers is being orchestrated to scare the Tory party and the electorate about the consequences of a no-deal Brexit. Ministers insist that, to the contrary, they are holding back some of the most blood-curdling stuff lest it trigger a public panic. The real issue with the documents issued by the government is not that they are alarmist and oozing with gory warnings. It is that these “technical papers” are skimpy and vague on critical detail and of not much help to anyone – a business, say, or a hospital or a food importer – who would have to cope with the havoc that would follow from a car-crash Brexit.

They offer statements of the bleedin’ obvious – “the free circulation of goods between the UK and the EU would cease” – and then follow up with vapid tips about how businesses might want to “consider your role in EU supply chains”. To say that the government has “a plan” for a no-deal Brexit is to abuse the English language. The recommendation to businesses trading across the border between Northern Ireland and the Republic is to “ask Dublin” what they should do. Phone a friend, eh? The logistics company, ParcelHero caustically observes that the government’s advice on how to cope with a no-deal Brexit is as much use as the Protect and Survive booklets issued during the cold war, which told people that the way to respond to a nuclear attack was to “use tables if they are large enough” to hide from the blast.

Dominic Raab, the Brexit secretary, has tried to put a cheery face on his department’s handiwork. He accepts that the impact of a bad Brexit wouldn’t be nice, but claims that the worst effects can be mitigated if only the nation is prepared to greet disaster with optimism and resolve. A campaigner for departure in the referendum, Mr Raab extols us to believe that Britain is capable of “rising to the challenges and seizing the opportunities”. Men of Britain, he is talking to you. If we get cut off from supplies of Danish sperm, Mr Raab will be expecting you to seize your, er, opportunities and rise to the challenge and show some patriotic spunk.

A sperm shortage would be one of Britain’s lower-order problems in the event of a departure without a deal. Philip Hammond, the chancellor, has published a letter predicting dreadful consequences for the economy if Britain crashes out of the EU next March. The Treasury guesses that it would take a very big bite out of economic growth and add £80bn to government borrowing. The Brexiters scorn those figures and the rest of us are entitled to be suspicious of the accuracy of this forecast. Only when we are some way past Brexit will it be possible to make a solid assessment of all its consequences.

What we can say now is this. There is already a price for Brexit. It is costing us now. One cost is the investment decisions delayed, cancelled or relocated because of Brexit uncertainty. Another price is in the already large amounts of thought, time and cash expended by business, government and many other organisations on contingency planning. That energy and money could have been used more productively elsewhere and can’t be recouped even in the event that Brexit turns out all right. There is an unrecoverable bill for precautionary measures to ameliorate the impact of a bad Brexit, such as telling pharmaceutical companies to assemble crisis-level stockpiles of medicines.

Then there is the big opportunity cost that Britain is already paying for Brexit. All the other things that its politicians might be doing, such as remedying the shortage of affordable homes or addressing the crisis in social care, are thrust to the margins because Brexit is so all-consuming.

The end of frictionless trade with the rest of Europe would cause massive disruption. Photograph: Gareth Fuller/PA

The price escalates dramatically in the event of a no-deal Brexit. Not only would there be no future agreement on trade, all the understandings that have already been reached with the EU would be vaporised. There would be no assurances on the future of British citizens living in EU countries or on the future of EU citizens living in Britain. There would be no agreement on the Irish border nor on co-operation against crime and terrorism.

A no deal could come in one of two forms. The less apocalyptic, but still highly turbulent version would see the negotiations grind into deadlock before collapse. Britain and the EU would then announce that they were abandoning hope of coming to a comprehensive withdrawal agreement. This would be followed by crisis talks in the short time left before Britain departs to try to agree emergency measures in key areas to avert complete chaos. That would be by no means pain-free. Without any understanding on trade, customs checks and tariffs would go up the moment that Britain left. The people who run our ports warn that the abrupt termination of frictionless commerce with Europe would lead to motorways turning into giant lorry parks accompanied by massive disruptions to supply chains.

The transition period currently agreed would become null and void. Absent that plan, which envisages a glidepath out of current trading arrangements, there would be a free fall. This is the milder version of a no deal. It is an outcome that is being talked about with increasing frequency by significant players in the EU and by ministers here.

The entirely unmitigated cast-strength version of no deal would see the negotiations collapse in bitter acrimony and few, if any, remedial holding agreements to try to avoid a total calamity. The National Farmers’ Union forecasts disastrous consequences for the food supply. The British Medical Association says there will be alarming implications for the health service, including delays in the diagnosis and treatment of patients with life-threatening conditions. You can dismiss all this as just scaremongering, as the Brextremists like to do when their fantasies collide with someone who might know what they are talking about. Or you can think that the many commercial and professional bodies that are scared rigid by the thought of a no-deal Brexit might be sober people with serious concerns who feel it a public duty to share their alarm.

Britain is not at all prepared for a no deal and neither is the EU. Because the consequences would be so horrendous, it is still often thought that a way will be found to avoid it. On that rests the assumption that there will be something called an agreement in the end, even if it is an almighty fudge that leaves a lot to be resolved after Britain has left. Against that, you have to observe that there has been so much miscalculation about this already and the political context is so febrile that the wise man does not entirely rule out the very worst-case scenarios. So check the size and robustness of your kitchen table and have your family practise duck and cover.

• Andrew Rawnsley is an Observer columnist