The main Brexit news today is on Ivan Rogers' resignation letter, which aims a not-so-subtle bullet at the government's Brexit strategy, or rather its lack of one.

The letter reveals that if there is a Brexit plan, no-one has bothered to inform our man in Brussels about it. "We do not yet know what the government will set as negotiating objectives for the UK's relationship with the EU after exit," Rogers wrote to staff as he departed.

The letter insinuates that UK Representation to the EU (UKREP), one of the few bodies with a working knowledge of our future negotiating partners in Brussels, is being ignored by Downing Street, presumably because it is seen as insufficiently loyal to the Brexit cause. "The government will only achieve the best for the country if it harnesses the best experience we have – a large proportion of which is concentrated in UKREP – and negotiates resolutely," Rogers says, pointedly.

It appears that a Brexit plan is not the only thing missing. With just three months to go until arguably the most important negotiations in Britain's history, the team was still nowhere near put together, nor communicating effectively. "The structure of the UK's negotiating team and the allocation of roles and responsibilities to support that team needs rapid resolution," the letter says. "Serious multilateral negotiating experience is in short supply in Whitehall, and that is not the case in the Commission or in the Council."

Rogers ends by encouraging his fellow civil servants to "continue to challenge ill-founded arguments and muddled thinking" and "never be afraid to speak the truth to those in power".

The message is quite clear: We have insufficient negotiating capacity, a British team which is not coordinating between Whitehall and Brussels – let alone Geneva where we will have to extract WTO schedules – insufficient understanding of the opposing negotiating team, no plan, and a political leadership which treats sober reflection and strategic caution as unpatriotic sacrilege. It's now 2017 and everything seems unchanged from where we were when Theresa May entered Downing Street.

So that's where we are. But peer behind the main headline and take a look at the less-reported but equally crucial report released this morning by the environmental audit committee. It gives you an impression of the scale of the danger hurtling towards Britain in just one area – farming and the environment – while it sits, unprepared, without a team or a strategy.

Firstly, economics. If the government leaves the single market and customs union and fails to secure any tariff exemptions, farmers face devastation. Ninety-five per cent of our sheep exports go to Europe, but these will face a whopping 30% tariff. Dairy exports would be 36%, beef up to 50%.

This is sector which is already eking out a marginal existence. These tariffs, if they hit, are going to be ruinous. And that's not the only area farmers are likely to lose. The committee reported that witnesses feared agriculture would be the sacrifice Westminster makes in future trade deals in order to secure a role for British financial services. After all, investment banks provide much more money to the economy, and agricultural exports are far more vital to countries in, say, South America. Cheap, hormone-fed beef is likely to then flood the UK market, further eradicating domestic farming's economic viability and the high standards of animal welfare and public safety which consumers have come to expect.

Farmers used to be protected by EU subsidies, but the future of these is uncertain. Ministers have pledged to continue them until 2020, but what happens after that is anyone's guess. As chair of the committee Mary Creagh said: "It was concerning that the environment secretary gave my committee no reassurance that there would be subsidies for farmers after we leave the EU."

Without those subsidies, pork and beef producers would close up shop. Cereals might be able to make it – it'll be touch and go. Poultry would probably be OK. Everyone else has a major problem. It would constitute a very violent and sudden change to Britain's farming industry and its countryside. EU farm subsidies currently make up 50% to 60% of UK farm income.

It's not even really clear if we could legally continue the subsidies under WTO membership, which brands them 'market distorting'. The EU subsidies are part of a specific agreement with the WTO. Whether Britain could claim to still be part of it after Brexit is up for question. That too would require negotiation, of the type which Rogers warned we were failing at, in terms of capacity, coordination and leadership.

And then there is the law, which is arguably the most devilishly complicated part of the Brexit puzzle. The government plans to copy-and-paste EU law into British law using the unfortunately named great repeal bill. The committee estimates that this will fail to protect one third of the 800 EU environmental laws currently in force in Britain.

Here's the thing: you can copy-and-paste the text of a law, but unless you recognise the European Environment Agency, the European Commission and the European Court of Justice, it is zombie legislation. It can't be enforced and it can't be updated to reflect new scientific understanding. As the committee found: "Simply transposing legislation without replacing the governance arrangements will lead to significant weakening of environmental protections in many areas."

These are the types of endless problems which are about to hit us. And we're running out of time. It's not just Article 50 which counts. It's the breathing space individual businesses have to make long-term decisions. That's why banks will start to announce their plans to move offices next month, so they have a chance of establishing themselves in Europe before they lose passporting rights in 2019. And that's why farmers need to make key decisions on their future now, because long supply chain planning decisions in the sector require a mid-2017 action for results two years later.

In both these disparate cases – the City and farms – the uncertainty of Brexit and the lack of a plan means you take decisions which maximise your room to maneuver down the line. So City firms move admin jobs to the continent, which they frankly wanted to do anyway. And farmers start ploughing grassland as a means of securing flexibility for the future. By the time the government figures out what's going on, the practical effects of the uncertainty will already be felt in countless individual decisions, made early due to the lack of information from Westminster.

That's the scale of the challenge and the severity of the time frame which Britain faces. Over half a year since the referendum, there is no sign of a grown-up approach to the challenge, a tactical approach to the talks, or a sensible use of the finite resources Britain has to use in addressing them. Instead, there is the strange new political mood: Of historic mission, instinctive distrust of critical thinking and an almost religious zeal in which anyone who disagrees with you is branded an enemy of the people.

Ian Dunt is the editor of His book – Brexit: What The Hell Happens Now? – is out now from Canbury Press.

The opinions in's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners.