Catsmate, manufacturing accounts for the majority of Britain's exports, from JCBs to wind turbines and the majority of Britain's exports do not go to the EU.
The UK has a significant trade surplus in services, a much larger deficit in "goods" (which includes manufacturing but also raw materials, agricultural products and so on).
We're consistently outperformed on the global stage by EU colleagues so the EU isn't the issue. Please bear in mind that the likes of Bamford and Dyson want to make it cheaper to import goods manufactured overseas to the UK not to export to the rest of the world.
The idea that exports are all going to stop is false. The idea that we should look only inwardly to the EU when there is a whole world out there is short sighted.
You're probably the only one suggesting that "exports are all going to stop" - yet another strawman from you, this really is getting tiresome - but the idea that we cannot compete globally while in the EU is debunked by the fact that the proportion of exports outside the EU has increased over the last few years whilst we've been members of the EU.

OTOH making it harder to trade with our single largest trading partner, the EU does seem like a pretty silly thing to do.
Of course there is uncertainty at the moment, no deal has yet been done or can be done until article 50 is declared, but there will be a deal.
Of course there will be a deal with the EU, the question is "how bad a deal ?". Paris, Frankfurt and Dublin are eyeing up our financial services business in the EU as a starter.
Our government will be grown up about this and will be respectful.
The squabbling, infighting and empire building being done by BoJo, Davis and Fox doesn't give me a great deal of confidence in this.
Both sides will have to be prepared to compromise.
Who compromises the most depends on who has the most to lose and who has the most skilled negotiators. Again, the UK has the most to lose and the less experienced negotiators, not confidence inspiring.