The WTO makes no deals for tariffs and quotas which we will be under without trade agreements, because every other major country is in trade agreements with others which specify points about countries outside those deals.
I'm really sorry springing but you're demonstrating a distinct lack of understanding of the issues now and your arguments are clouded by your desired Brexit solution.
So as an economist let me outline my scenario from Brexit.
Short term (1-2 years) There is a significant period of economic slowdown/recession. The value of the pound falls and as such import costs and costs to businesses rise so at the same time we have an increase in inflation, some major organisations leave the UK and others reduce their FDI in UK firms or are encouraged not to invest at all. At the same time UK firms will not be optimistic about the near future and lower their investment levels (which are already low despite incentives). Consumer confidence falls and thus so does consumption.
This makes the recession cycle deeper and unemployment goes up rapidly. Output, investment fall, but because the value of the pound continues to be low the costs to firms will increase ( you know cause oil will be more expensive etc)
At the same time the UK credit rating on gilts will fall and interest rates go up so we will be in even larger budget deficit, and most likely unable to counter the effects with public spending.
Because of the decreased international competitiveness (caused by rising costs due to inflation/export tariffs) we will have a weaker hand when negotiating trade deals with both the EU and the US and therefore in the long run be very much worse off.
Most especially the loss of investment from firms both domestic and in FDI combined with the neccesary lower public spending which will be necessitated by lower tax takes and higher benefit costs will greatly effect the long term productive capacity of the economy.
It may not be that cataclysmic but I'm going to ask other posters to see if they think my scenario is more believable than yours?