He goes nuclear. Standing in Faslane Trident submarine base, finger on the button, our prime minister’s Brexit strategy is MAD, mutually assured destruction. His preposterously nicknamed “Brexit war cabinet” met for the first time on Monday. Every minister has been “turbocharged” to prepare for the great no-deal blitz in three months’ time. The idea is to terrify the enemy: the effect will be to petrify ourselves, shocking and awing us into understanding the full implications of no deal.

“There are no areas of relevance to the economy where the UK, EU and the business community are prepared well enough for no deal,” a CBI report said on Monday. “No one is ready,” nor can they ever be, was the warning. A few sandbags will only hold back the flood waters briefly. In response, the government announced a £100m public awareness information bombardment: nine out 10 businesses and exporters are unprepared for no-deal obstacles – the road haulage licences, phyto-sanitary vet checks, pages of manifests and customs dockets to be stamped and authorised, delaying them at borders.

An election fought on a no-deal Brexit platform would be winnable by the considerable combined forces of reason

Politically the nuclear analogy is apt. Those who remember the cold war civil defence Protect and Survive leaflets of the 1980s – telling us to block up windows and hide in the cupboard under the stairs, with torches, tins, water and sanitation buckets – recall those chillingly matter-of-fact warnings. A five-mile radius of total obliteration and indefinite radiation fallout. Designed to show the enemy we were serious, it struck more horror at home and galvanised recruitment to CND.

Boris Johnson’s mock-Churchillian gambit will have the same effect. The more billions he wastes on preparations – the more talk of empty supermarket shelves, medical shortages or 10,000 riot police standing by – the more the madness of all this will dawn on people. Blitz spirit? British pluck and nerve? Not a chance in the face of even mild inconveniences.

The pound fell again on the news of these turbocharging Brexit plans: how will that please people setting off on holiday – let alone a stream of closures hard on the heels of the departing Ford and Honda plants in Bridgend and Swindon?

No doubt the nation is as plucky and full of nerve as ever it was when facing a genuine existential threat – Nazis across the Channel or alien invaders. But there is no enemy attack. This is just us bombing ourselves – breaking away, of our own accord, for notions of “freedom” and “sovereignty” that turn out to be a miasma, all losses and no gains. No amount of faux-Churchillian anti-Johnny-Foreigner bombast will cover up what Johnson’s Brexiteers have done to us. Nor do the 27 civilised EU nations – not Angela Merkel, not Emmanuel Macron, not the politely erudite Michel Barnier, nor the new European commission president, Ursula von der Leyen, fit the bill as tyrants to blame for our self-inflicted turmoil.

The cabinet is indeed a scary spectacle of diehard, hatchet-faced rightists and Ayn Rand fans. Designed to spook the EU, they are likely to repel UK voters, this rogues’ gallery with a high quotient of shysters, liars and low-calibre egotists, without the brains or crowd-pleasing bonhomie of their leader – he chose none to outshine him. (Gavin Williamson in charge of the nation’s children? Really?) Johnson’s heavy hitter is Michael Gove, not a public-friendly face. The very name Dominic Cummings, deviser of “take back control”, is supposed to strike panic into all hearts, but the dark arts master with a strong belief in genetic determination is no more a wizard than Lynton Crosby, deviser of Theresa May’s miserable “strong and stable” campaign motif. There are good reasons not to fear any of them.

Johnson’s hard-right, hard-Brexit crew alienates at a stroke at least a quarter of 2017 Tory voters who are remainers, and maybe more who won’t like the smell of this cabinet’s hostile environment. Dominic Raab’s first outing as foreign secretary on Monday’s Today programme gave an unsavoury flavour of what to expect: he suggested Vote Leave always said no deal was on the cards – but it never did. As is his wont, Raab turned nasty when rightly challenged by presenter Mishal Husain. They will say anything: he claimed negotiating a free-trade deal would be easier after a no-deal crashout, as if the chaos caused to both sides or Britain’s £39bn unpaid debt would ease future relations.

Here is the Johnson government’s predicament: he is not elected, he has no mandate, and no deal was never raised in the referendum. No deal is not the will of the people then or now, only 25% supporting it. His new term, “the undemocratic backstop” is a nonsense. Downing Street on Monday confirmed that Johnson is refusing to meet EU leaders until they abandon the backstop that keeps the Irish border open, as stipulated in the Good Friday agreement, and keep intact the EU single market, as envisioned by Margaret Thatcher.

Though Johnson said in Scotland he wanted to “go the extra thousand miles”, he stuck to that impossibilist position. He may sweep up Faragists but he will not take most of the country with him.

His new-leader bounce has been modest: an average of polls gives him 30%, his 6-7% increase taken from the Brexit party – no sign of reaching across lines. With four parties in play, Johnson is not yet the proven winner he promised his party – and has no hope of “uniting the country”. As he tours the land with a bag full of spending promises, he will need to make them good soon – but no deal will leave him with thin Treasury receipts and heavy compensations to pay for all the losers, before any new spending.

Boris Johnson says he’ll spend, but who will pay? Read more

Better to run for an election before his promises turn to dust. Best to go before 31 October, the disaster date when either he compromises, the European Research Group explodes and Nigel Farage eats a fat slice of his vote, or he crashes out of the EU when the chance of winning an election amid no-deal mayhem bodes even worse. Either way, the Johnson regime will not last long: the only question is whether he brings down the country as he goes, leaving us ruinously Brexited with no deal.

His one hope is the feeble opposition, letting Jo Swinson sweep up remainers appalled at Labour’s pitiful response to Johnson’s Brexit plan. A quick election means catching Corbyn still in post, the lowest polling opposition leader in history: polls show Labour’s vote jumps up without Corbyn. There is no predicting the outcome, but there is great strength in the anti-no-deal plotters in the Commons, with Keir Starmer gathering with the immensely powerful Tory backbench rebels ready to prevent no deal. The serried ranks of grandees, from Oliver Letwin and Philip Hammond, to Rory Stewart and Dominic Grieve, will be formidable opposition to Johnson. Either they will bring him down, or Johnson will call an election himself to avoid that fate.

In that rebellious atmosphere, and despite the handicap of Corbyn, an election foolishly fought on a no-deal Brexit platform would be winnable by the considerable combined forces of reason. No deal is a losing cause that not even Cummings’s dark arts can turn into a winner. Bring it on and Johnson stands a high risk of being seen off before his 100 days are up.

• Polly Toynbee is a Guardian columnist

• This article was amended on 30 July 2019 to clarify a reference to Margaret Thatcher and the EU.