UNLESS you’re greatly excited by the prospect of a celebratory coin, I fear you’re going to find the end of the week a bit anti-climactic. It will certainly be less dramatic than, for example, the replacement of the 10 shilling note with the 50 pence piece. In the meantime, very little will change. The UK’s departure from the EU may be momentous, but the point of departure is merely a moment.

The changes could be huge, or relatively minor. Whichever they turn out to be, and whether you then regard them as gains or losses or – as most normal people are likely to – a bit of both, they will happen not in an instant on Friday, but over months, years, and probably decades.

If Brexit changes the shape of Britain as significantly as coastal erosion (bad) or globalisation (good), it’s going to do so on the timescale of those transformations. Any little lurches, dips or boosts will be part of a long trajectory. It would be nice if that were an upward one, but in any case the overall trend will become apparent only when we can look back at the effects of literally thousands of small decisions.

Concentration on issues such as the Withdrawal Agreement with the EU, or the likelihood of a US trade deal, or some sort of CANZUK free movement, can miss the fact that these apparently monolithic settlements are made up of details. The sole change Brexit makes, in one sense, is that the UK government has control over which to continue, which to adopt, and which to abandon.

That control, however, is limited by all sorts of things. Not merely horse-trading with the EU or countries such as China, the US or the Commonwealth and Anglophone nations for large trade deals, but with Parliament, the individual nations of the UK, and the electorate.

The best way to make those calculations is not to claim that some things – whether it is ECJ oversight, Scotland’s dependence on migrants, or the inviolable sovereignty of UK fisheries – are not up for negotiation, but to make rational calculations about their long-term value.

Some EU restrictions (on GM crops, for example, or insisting that salad is washed in chlorine, but that chicken isn’t) are inconsistent, protectionist or have dubious scientific foundation. The same applies to likely US demands on, say, the duration of patents or copyright.

One objection to the EU was that the single market’s “free trade” is in reality a restraint on trade with other countries without Brussels’ say-so. Tariffs are a minor part of that; with the exception of Donald Trump, there’s near-universal acknowledgement that they’re economically damaging all round. The real contest is over regulatory alignment, and who imposes it.

Any economic advantage in Brexit will come from the freedom to adopt or reject such rules, and since both UK trade with the EU and the EU’s share of world trade have been steadily declining for years, that offers obvious opportunities. But EU countries remain hugely important to UK firms, so we will also want divergence to be gradual or confined to non-EU trade.

The EU’s fear must be that UK detachment from its regulatory control is a success, which is why it wants to make remaining within it a condition of a wider deal. Short-term economic priorities suggest we shouldn’t try to change much, while the short-term political aim for the government is to make it look as though real change has been achieved or is at least on the way.

The long-term aims, political and economic, that would bring real gains, however, are to expand freedom to trade and freedom for each country to adopt only those restrictions – on food standards, harmonisation of financial practice, health and safety regulations and the like – in their individual or mutual interest.

In an ideal world, the government (and the voters) would pick and choose on the basis or rationality, utility and maximising competition: the very things obstructed, obscured or distorted by over-arching “free trade” deals and domestic political demands. But the world is not ideal but practical.

In practice, continuing to abide by some EU rule on kettles won’t be a betrayal of Brexit, and by the same token, dropping some similarly pettifogging regulation on toasters is unlikely to lead to avoidable deaths, economic disaster, or global war. If the advantage of Brexit is the power to pick and choose, its disadvantage is the same thing, unless we have the sense to do so wisely, and with a sense of proportion.