Britons have spent £4bn stockpiling goods in preparation for a possible no-deal Brexit, new research suggests.

One in five people are already hoarding food, drinks and medicine, spending an extra £380 each, according to a survey by the finance provider Premium Credit. The survey found that about 800,000 people have spent more than £1,000 building up stockpiles before the 31 October Brexit deadline.

If the UK leaves with no deal, businesses predict there will be short-term supply problems, which the government says it is mitigating.

Similar research in the weeks leading up to the original deadline for the UK to leave the EU found that about 17% of the population had spent some money building up supplies, with a total stockpile spend calculated at £4.6bn ahead of the 31 March deadline.

Of the people who are stockpiling, 74% of those surveyed said they had bought extra food, 50% bought medicines and 46% bought drinks.

Brexit-related stockpiling is also hitting cashflow, according to the report, with companies taking out credit to cover the cost of insurance and other fixed costs.

Adam Morghem of Premium Credit said: “The level of stockpiling by British businesses and households is well documented, but there has been little focus on the impact this has had on cashflow, which has been quite negative.

“Interestingly, over the past three months we have seen an increase in clients looking to use premium finance to pay for their insurance, and we believe a key factor behind this is the impact of stockpiling on cashflows, forcing more businesses and households to spread the cost of their insurance.

“Businesses should also check with their brokers to make sure their stockpiled goods are properly insured.”

Last week, the boss of Pets at Home revealed the business was hoarding pet food, and Domino’s Pizza said it has started stockpiling toppings.

The super-rich are also importing more luxury cars ahead of the Brexit deadline in order to avoid tariffs that might be introduced following a hard Brexit. More than 3,800 luxury cars were imported in the past year, a 16% increase on the previous 12 months, according to the law firm Boodle Hatfield.

“A no-deal Brexit could mean luxury car imports become 32% more expensive overnight,” Fred Clark of Boodle Hatfield said. “There is a possibility that moving cars into and out of the UK will become more difficult if the UK leaves the EU with no deal. More individuals are now taking that risk seriously and bringing vehicles into the UK from the EU.”