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Boris Johnson went on the attack after a string of Conservative gaffes overshadowed the start of his election campaign, declaring his intention to get his “oven-ready” Brexit deal through parliament quickly.

But in the first full week of campaigning Johnson also seemingly committed a gaffe of his own when he insisted exporters in Northern Ireland would “absolutely not” have to fill in extra forms or submit to checks when they sent goods across the Irish Sea.

This contradicted the Brexit secretary, drawing accusations from the opposition and MEPs that the prime minister – who also said Northern Ireland had a “great deal” since it would stay closer to the EU than the rest of the UK – did not understand his own exit agreement.

The business minister Kwasi Kwarteng insisted later that the prime minister was correct, despite the deal apparently requiring customs declarations for all goods shipped from Northern Ireland to Britain.

Keir Starmer: Tories' doctored TV footage is 'act of desperation' Read more

The Conservatives also came under heavy fire for doctoring footage of Keir Starmer, the shadow Brexit secretary,making it appear as if was unable to answer a question on Labour’s Brexit position, when in reality he provided a lengthy answer.

But the Tories received a big boost when Nigel Farage said his Brexit party would not contest 317 Tory-won seats to avoid splitting the leave vote after Johnson committed to exiting the EU by 2020 – see below – and pursuing a Canada-style trade deal.

Many observers saw this as a possible gamechanger, although the polling guru Prof Sir John Curtice told the BBC its likely impact should not be exaggerated. It might, though, wipe out any potential Liberal Democrat advances from a Lib Dem, Plaid Cymru and Green pro-remain pact, Curtice said.

More good news for the Tories came with the release of a study revealing that more than 1 million low-income, mainly leave-supporting voters who did not vote in 2017 are planning to do so this time, potentially affecting results in at least 40 seats.

In Brussels, the incoming president of the European commission, Ursula von der Leyen, asked the UK to nominate a new UK commissioner – a request Johnson looked likely to comply with, albeit reluctantly – and her predecessor Jean-Claude Juncker described Brexit as a perpetual cycle of “promises, promises not kept, and lies repeated over and over again.”

On the remain side, three tactical voting sites have been or are about to be launched advising people how best to vote to avert a Conservative majority – although unfortunately all do not agree. And Labour promised “managed migration” for EU nationals in the event Brexit happened, without saying how it would manage it.

What next

But can Johnson take Britain out of the EU by the end of 2020?

Lest anyone forget, what has happened thus far on Brexit is merely the exit deal: the hors d’oeuvre. Assuming the agreement is eventually passed by parliament – a process that could take up more than a month – and the UK subsequently leaves the EU by 31 January, there remains a deal on the future relationship to be negotiated.

The time available to negotiate this umbrella agreement, covering security, political and, above all, trade ties, has already been cut from two years to 11 months. The government insists it will never extend the transition period, but few experts believe it is possible to negotiate a deal and get it ratified around the EU in that time, raising the possibility of crashing out on 31 December 2020.

A first flashpoint next year could well be over who leads the talks for Britain: the Department for Exiting the European Union or Downing Street? Then the two sides must decide whether to pursue several parallel agreements, separating trade from issues such as science, education and international development.

All this will need to be accompanied by a mammoth legislative programme and a Herculean effort to get new technical arrangements up and running – for example, HMRC has to put a new border in place in the Irish Sea. It is almost inconceivable that all this could be achieved by the end of 2020.

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In the Observer, Nick Cohen says there is no chance of avoiding a difficult political choice in the December election:

The only way, it seems, to stop one extremist in #NeverNeverLand is to vote for another. The only way to save #NeverNeverLand from a rightwing disaster is to vote for a leftwing disaster … Britain does not face a binary choice. After Johnson’s purge, the Tory benches will be full of hard-faced hacks determined to impose Brexit, whatever the cost. Momentum will ensure the next batch of Labour MPs will contain more incontinent cranks than any country deserves. We are about to elect a parliament of freaks and fanatics … [But] we may have to experience a Johnson Brexit or a Corbyn government before enough voters turn against them. It is as if large sections of the population have reverted to childhood and must learn all over again that there are no fairies in our #NeverNeverLand, only monsters.

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Sky’s Lewis Goodall pinpoints the dilemma that the Brexit party’s decision not to contest 300-plus Tory-won seats poses for remainers: