Absolutely get on with it. Uncertainty creates more collateral damage than a short sharp shock.
We default to WTO which mitigates the initial impact (or puts the tourniquet on), then unravel the rest.
Business & trade will sort out the rest.
The question of tariffs is the easiest one to resolve in the case of a no deal Brexit. Because there's a set of global trading rules to fall back on.
What about the other hundred issues that we haven't prepared for, e.g.:
- Suddenly having a hard border in Ireland with no free movement of people, goods or services. Have to set up the infrastructure to charge tariffs, check passports etc. etc.
- Suddenly having to check and charge tariffs on all goods coming into UK ports from the EU. Have to expand infrastructure there too
- WTO rules don't cover aviation so all flights are cancelled until Britain can enter into a free skies agreement
- Financial firms suddenly can't undertake business for European clients because there's no longer any passporting rights, until another agreement is put in place
- EU citizens living in the UK, and UK citizens in the EU, suddenly lose their rights to residence, healthcare etc. until an agreement covering this is put in place
You might say - it's OK, we'll work things out on the fly, necessity breeds inventions etc. etc......but you've seen how the UK government operates, you've seen how the EU operates; there is zero chance everything gets resolved and work out in any reasonably short time horizon. They're just not competent enough to solve that depth and complexity of problem.
If Britain had begun preparing for a No Deal Brexit on Day One after the referendum, then there's a chance they could have worked everything out by now for at least an orderly transition.
But they haven't, so it would be the biggest chaotic disaster anyone could possibly imagine.
The majority of MPs are at least savvy enough to know this, and so will do whatever they can to avoid that scenario. Which, as I say, practically means delaying Brexit until they have some clue.