It depends how long it goes on for, b4 we start making deals and with whom. Suppose it goes on for 7 yrs before a substantial deal is settled with USA or EU. Then I predict for UK:
National Debt >> % of GDP.
longer delays than we're used to, to get spare parts (washing machines, cars, computers, pianos, medical equipment ,etc.)
Poorer quality goods noticeably in shops (spare parts, clothing, other things), more expensive for good quality goods.
More £1 shops.
More empty shelves on supermarkets; Sainsburys had a period of extended logistics failure maybe 8 years ago, like that was, but widely in many retailers.
Loss of jobs in manufacturing (-> economic recession in local places) & financial services (-> braindrain flight, contraction of economy in London).
More spaces for health care job training, but lowering standards what they do.
Stories in news about people who died due to lack of some medicine or medical equipment due to difficulty getting it in time.
Higher Inflation. Deregulation will prevent decline in foreign investment in UK, but that will lead later to bitter resentment at Russians owning Chatsworth House or somesuch.
Potentially huge changes in research sector; loss of less prestigious research institutes & the smaller research intense Universities becoming far less ambitious.
More flogging of education: selling more spaces to get nursing or medical degrees to international students.
More Indians & Chinese visibly around, as they get visas in exchange for access to their markets.
We're heading towards an energy generation crisis deal or no deal.
Impacts on EU of No deal with UK for 7 yrs: changes in % of economy in specific sectors but not much change over all.