Java,
The big danger is delays in (ludicrously convoluted) supply chains and inflation, coupled with a lack of confidence in GBP.
Some WTO tariffs, by the way, are over 10%. They are not all small numbers.
If we get significant inflation and falling currency, the traditional response would be higher interest rates. However with a significant recession, that would push us into depression.
The alternative would be to hope that the inflation was a one off spike (it should be as tariffs won’t continue to go up). However that will leave people who are income based considerably poorer.
If we do have a ‘no deal’ Brexit, the policy response will have to be very carefully managed. Personally I do believe that the cooler headed (and most influential) Europeans realise that this is not a zero sum game and punishing us will also be really painful for them (and possibly also cause EU break up via a continental recession and Italian Euro default).
I am not a Brexiteer, it is an unpleasant and unnecessary process. However, I also believe the Euro (and thus the EU, regardless of the ludicrous claims of some that they are not the same) is a doomed project. Maybe taking the pain upfront rather than a few years down the line will work out well for us.