After three years we may be about to find out what Brexit means, at least in the minds of MPs. The prime minister’s deal tells us little more about the future EU-UK relationship than that we would leave and work the rest out later. MPs rejected that premise, and have now taken the logical step that the government refused to countenance, to try to resolve before we leave what Brexit really means. A vote last night put parliament into the driving seat and all options will now be tested. But there are some hard truths waiting round the corner.

Perhaps MPs will not quickly succeed in finding a majority Brexit meaning, perhaps the PM will finally get her way and her deal will pass. But either way we are at long last getting closer to the real debate, because even if the current deal passes we will need realistic goals for the next stage of negotiations. The outcome of the debate, we can be fairly certain, is that Brexit means that the UK cannot have everything we want.

The prime minister aimed for a Brexit that kept her party together by pretending the opposite. Her Chequers proposals simultaneously imagine a close UK-EU relationship, with shared rules on goods and customs partnership allowing frictionless trade and no border infrastructure in Ireland, and a distant one, in which the UK is able to bestride the world signing trade deals. We would have great services access to the EU, but not have to follow its rules or accept freedom of movement.

Such a trade relationship is sadly undeliverable. The EU slightly fudged the issue by parking some vague form of the proposals in the aspirational future Political Declaration, and ensured no leaking of unrealistic proposals by saying the Withdrawal Agreement could not be reopened. As negotiators they know the latter isn’t strictly true, but it was easier to do this than to be honest.

Thus the deal puts the UK as a patient in a waiting room while waiting to see if the technology to turn us into a bionic man might come to be available. There are other undeliverable Brexit visions that have yet to be dismissed, and will probably continue to cloud the debate for a while.

Advocates for a Free Trade Agreement (FTA) point out that this has already been offered by the EU. Which is has, but only for Great Britain, with Northern Ireland in a completely different arrangement. Unacceptable to the UK one assumes.

Supporters of the “Malthouse compromise” imagined that there were already technology solutions available to avoid border infrastructure in Northern Ireland, such that an FTA relationship was perfectly possible. Sadly their imagination was just that, and asked to name any border without infrastructure outside the EU they could not. Nor could they even name one country expecting this to happen in the next few years.

Even if technology was available, or the EU had made such an offer, supporters of an FTA might also have to explain why the UK’s access to services markets in the EU had declined so markedly, why frictionless trade was not possible, and why we still appeared to be following all manner of EU rules without being consulted. The latter is going to be a problem for any option in which we leave the EU, given that trade considerations will always mean the UK tending to follow the EU path (known as the Brussels effect).

Then there is Labour’s unicorn proposal for a customs union in which the UK gets as much of a say over EU trade policy as we do currently. Some say it’s possible, but let’s be realistic, we are not going to be that influential. We’ll have to follow EU trade policy, and try to negotiate parallel deals to the EU, which will be far from easy.

It should also be noted that to ensure no border infrastructure in a customs union we will also have to follow a significant chunk of EU rules over goods without consultation, and once again without much access on services. It’s not a panacea either.

The Norway option, or “Common Market 2.0,” has the benefit of retaining access on services, and gives us some limited say over rules we will follow. But not as much as we have now, and to get unchanged access to services you also have to accept freedom of movement. Some people will like the latter, but many think it is a betrayal of the referendum. Not to mention the fact we’ll still need a customs union or arrangement to prevent Northern Ireland infrastructure. No easy choice this.

So, just leave and be done with it, say the no-deal advocates. But they then talk about mini deals with the EU, because it really isn’t sensible to have no economic arrangements with your primary trading partner, given the likely economic shock. So we’re back to the problems above. If you want a quiet life in the future no-deal doesn’t deliver.

This leaves us with those wanting to revoke Article 50 or have another referendum. You can hear the cries of betrayal already, and that doesn’t change if a million people march in London to “Remain.” Westminster won again, goes the narrative, particularly in those areas like the midlands and Lincolnshire that don’t appear to have been signing a revoke petition in great numbers.

In ever decreasing circles this is where we have been for three years. There is no solution without cost, but nobody wants to talk about the costs, only that the UK can have all the benefits of EU membership and all of the benefits of leaving. MPs were wise enough to see that leaving and waiting for something in the future was storing up trouble. But the alternative is to face the trouble now. There’s no perfect outcome, even if you may be able to shape whatever option you choose a little.

Just to add to the problem, many have spent three years persuading the public that perfection does exist, but these terrible Europeans or Westminster MPs are blocking it. So it isn’t just about MPs finding a solution, there’s also an education job to be done, against the backdrop of true believers preaching that if you just want it harder then perfection is within reach. That’s the mess we’re in, and good luck to MPs as they try to disentangle it.