You two are missing the point that someone will no doubt make as a counter to this logic that Britain will be able to negotiate whatever trade deal it wants because UKgoddamnitwhywouldntwestopscaremongering.
And the counter to this would be 'Wow, you mean like the trade deal that literally no other country on the planet has managed to negotiate'?
We are not going to get tariff free no hassle trade without EU caveats. EU caveats that Norway and Switzerland were happy to accept, therefore have tariff free no hassle trade. EU caveats that are unacceptable to countries like Canada who therefore do not have tariff free no hassle trade.