Not sure what this is showing, the UK's greatest current account deficit was just over £32Bn.
https://tradingeconomics.com/united-kingdom/current-account-to-gdp
Without an agreement the EU will have to impose strict border controls, the Single Market necessitates this. Without it, for instance, what is to stop somebody importing goods into NI from elsewhere under WTO tariffs that are lower than those of the EU, and then simply shipping these goods across a 'soft' border into Eire. One of the main criticisms of the 'smart' customs solutions is that they cannot "see inside sealed trucks".
I did read it, and it is an opinion piece, not fact. If your interpretation of his piece is correct, then why have Parliament not yet delivered what their sovereign people have determined is the nation's will ?
( And I recommend the Guardian article in buctootim's post. )
The British People are sovereign during the build up to, and voting for, a General Election. At all other times we are a secondary consideration. If it was the way you think it is, Brexit would have been signed, sealed, and delivered long since.