Maizie your assertion that a government cannot run out of money may well be technically correct - they can keep printing money. However the value of the currency can fall so low that the cost of imports and technology impoverishes the population.
There have been plenty of countries in this situation to a greater or lesser degree. Zimbabwe is a good example where for political reasons the whole productive ability of the entire country was shut down. Not just export ability, food production as well, adding to that widespread corruption and even after 30 yrs there has been little recovery. Currently we have Venezuela, Argentina and many other countries where the currency is worthless, where the largest banknote is worth 50p. To fill your car up you take a roll of notes that fills your pocket, all commercial transactions are done in hard currency usually US dollars.
This happens in the U.K, after WW2 Sterling was worth over 3 dollars since then our economy has gradually weakened and now worth $1.20, not a great performance. It’s not possible to predict what exchange rates are going to be after Covid 19, the US has its own problems, the Euro countries have their problems. Getting caught with no trade agreements is not a good position in a recession, so to balance the books, either austerity, higher taxation or sterling falls in value.