What we import from the EU will be more expensive under WTO rules so prices will rise. What we export to the EU (43% of all our exports) will be more expensive for them to buy so the EU will just buy what they used to buy from us more cheaply from other EU countries. Britain’s Tax income from Exports will fall, businesses who export goods will go under, jobs will be lost = less people to pay Taxes = Income Tax income will fall = less for the Government to spend on stuff like schools, police, unemployment benefits, housing benefits, the NHS, Social Care = Tax rises for those who still have jobs.
Still, we’ve now got the Navy tied up patrolling the Channel (to sink stray fishing boats and the odd dingy full of non-EU immigrants, or what’s the point? Everyone knows Britain is a paper tiger).