Playing devil's advocate here for a moment mate...
It's true that on November 1st with no deal, the EU will be obliged to apply tariffs on imports from the UK. But whilst there's a few exceptions, most tariffs are circa 10% or less.
However, the pound is already more than 20% down compared to the pre-referendum rates and would doubtless drop further if it became clear we're leaving with no deal. So the upshot is that even with tariffs applied, most UK exported goods would still be much cheaper than they were a few years ago. Exceptions like dairy could be given special subsidies, which we'd be free to do outside the EU.
And regards import tariffs on goods coming in, we don't have to apply them, at least not immediately. In the long term, unilaterally dropping your tariffs to zero, would make negotiating new trade deals more difficult, but even then not impossible. Instead of bartering with an offer to drop tariffs, we'd sit at the table with the threat to levy them if no deal is done.
For me the biggest fear is that inward investment into the UK from foreign businesses would be severely curtailed, and the ones already here would imo decamp in large numbers. It's not the tariffs per se, it's the supply chain "friction" and added administration costs and delays. I'm sure that would cost many, many jobs.
