An old New Yorker cartoon shows a middle-aged man at a drinks party saying to another: “But that’s enough about you, let’s talk about me!” This is Brexit Britain talking to the rest of Europe. To be sure, all nations are obsessed with their own affairs. A Polish joke has it that the entry for elephant in the encyclopedia reads “the elephant and the Polish question”. But most European countries have at least some accompanying sensitivity to what is going on around them.

I wonder how many people in Westminster this week even knew that the leaders of France and Germany were signing a new treaty of cooperation in Aachen; that the French president, Emmanuel Macron, deeply shaken by the level of support for the gilets jaunes protests, had launched a “national debate”, much like the one being called for in Britain; that Poland had been shaken by the senseless murder of the liberal, pro-European mayor of Gdańsk, Paweł Adamowicz, in an atmosphere of partisan conflict so bitter that the nation could not even unite in the face of such tragedy. Reflecting all this turmoil, the whole continent is gearing up for European elections in May which will be a battle royal between two fundamentally different visions of the European future – a conservative, nationalist one spearheaded by the Hungarian Viktor Orbán and the Italian Matteo Salvini, and a more liberal, internationalist one represented by the much weakened Aachen duo of Macron and Angela Merkel. Orbán and Salvini don’t intend to leave the EU, they intend to run it. So it’s not just the future of the UK that will be decided this year, it’s also the future of Europe.

This is the background against which our European partners are appealing to the UK, with a mixture of exasperation and desperation, to tell them what it wants. Because of Theresa May’s incompetent intransigence, the immediate choice before the country is “no-deal Brexit or delay”. There is only one responsible answer.

May under increasing pressure to delay Brexit as union leaders call for article 50 extension – Politics live Read more

Fortunately, there are enough people in parliament, supported by numerous individual members of the government, who recognise that we can’t go on like this. If two key amendments tabled with cross-party support are passed next week, parliament itself will be able to take the initiative in debates about Brexit every Tuesday – and if no way forward has been found by the end of February, the government will be instructed to seek an extension of article 50.

Before formulating the request for an extension, however, politicians would do well to stop for a moment and – unlike the man at the drinks party – look at it from the other’s point of view. If the UK is constrained by its laws and politics, so is the EU27. The key legal problem is those elections to the European parliament. European law says that the new parliament cannot legally convene on 2 July unless there are properly elected representatives from all the member states. If the UK remains a member state, but does not hold European elections, everything the new parliament does would be vulnerable to legal challenge.

Behind the legal problem is the politics. Some people in the EU really want the UK to leave, and would be happy to use this issue as a justification for pushing the recalcitrant Brits out of the door. Many more would in principle like the UK to stay, but are completely exasperated with London’s shillyshallying and feel it is more important for the rest of the EU to get on with saving itself. Then there are those who really want us to stay, including the likely next chancellor of Germany, Annegret Kramp-Karrenbauer (aka AKK) and other leading German figures who recently conveyed that message in an extraordinary, heartfelt letter to the Times. But they, too, are impatient for the UK to say what it wants. Specifically, as the European commissioner Pierre Moscovici puts it, the EU needs a “reasoned request” for extending article 50.

Play Video 14:49 Brexit breakdown: southern discomfort – video

Now here’s the rub. Most EU sources agree that it would be relatively straightforward to get an extension until 1 July (thus not significantly affecting the new European parliament). Those extra three months might be sufficient for the UK parliament to agree some tweaked version of May’s deal, or to put the goal of a softer Brexit (somewhere between permanent customs union and Norway plus) into the political declaration. They are nothing like enough to have the national debate we need and then hold a carefully prepared second referendum. Moreover, it is not until after the European elections, the appointment of four top people in the EU (the new presidents of the European council, European commission, European parliament and European Central Bank), and quite possibly the emergence of Kramp-Karrenbauer as head of a new German government, that we will have a clearer idea of what kind of EU it is we will finally be deciding to stay in or leave.

For clarity on both the British and the European side, we need another year, until 29 March 2020. Yes, I already hear a collective groan echoing from Durham to Delphi – but seriously, what’s a year when a century is at stake?

Quick guide Why extend the Brexit transition period? Show Hide Will the proposal solve anything? The mooted extension to the transition period is a new idea being put forward by the EU to help Theresa May square the circle created by the written agreement last December and the draft withdrawal agreement in March.

That committed the UK and the EU to ensuring there was no divergence between Northern Ireland and the Republic of Ireland.

But it also, after an intervention by the Democratic Unionist party, committed the UK (not the EU) not to have any trading differences between Northern Ireland and Great Britain.

The problem is that these are two irreconcilable agreements. They also impinge on the legally binding Good Friday agreement, which brought peace to Northern Ireland and in some senses pooled sovereignty of Northern Ireland giving people a birthright to be Irish or British or both.

If the UK leaves the EU along with the customs union and the single market then the border in Ireland becomes the only land border between the UK and the EU forcing customs, tax and regulatory controls. The backstop is one of three options agreed by the EU and the UK in December and would only come into play if option A (overall agreement) or option B (a tailor-made solution) cannot be agreed by the end of transition. The Irish have likened it to an insurance policy. The new EU idea is to extend the transition period to allow time to get to option A or B.

But an extension is problematic for Brexiters and leave voters, who want the UK to get out of the EU as soon as possible.

The Irish and the EU will also still need the backstop in the withdrawal agreement, which must be signed before the business of the trade deal can get under way. Otherwise it is a no-deal Brexit.

Extending the transition into 2021 would mean another year of paying into the EU budget. Britain would have to negotiate this but it has been estimated at anywhere between £10bn and £17bn. Staying in the EU for another year would also mean continued freedom of movement and being under the European court of justice, which Brexiters would oppose.

Since the May government (insofar as it still exists) will not prepare such a reasoned request, we on what I call the 3Rs side of the argument – the 3Rs being referendum, remain and reform – should do it ourselves. Some of our well-qualified lawyers and former officials should explore informally with European colleagues possible legal solutions to the genuinely knotty problem of the European parliament after 1 July. As important, our politicians should take a closer look at a continent in which everyone is facing challenges that have many of the same causes as the Brexit vote, and try to put our reasoned request in that wider European frame.

One of Britain’s chronic problems in Europe is that while there have been many pro-European British politicians, there have been far fewer who actually speak European, in the way that French and Germans, Poles, Spaniards and Italians instinctively do. For they start with both head and heart from the premise of a shared future. Even from pro-European British mouths, the phrase “remain and reform” can all too easily sound like “you must reform so we can remain”. The burden of our song should be the other way round, “we must remain so together we can reform an EU that needs it to survive and prosper”. That melody at least has a sporting chance of finding some sympathetic ears.

If we Brits are to get the time we need for the biggest political decision of our lives, we must speak not just plain English but also elementary European.

• Timothy Garton Ash is a historian, political writer and Guardian columnist