If it's help with paying the mortgage and the food bills, then that's a separate aim - achieving this and this alone would likely be achieved far more simply and at a much lower cost than UK plc buying up hundreds of aircraft. Buying up aircraft has the additional concern of wondering when air transport demand will substantially return and when airlines would be strong enough to buy aircraft from the Govt (instead of trying to lease them from a 3rd party !). Fundamentally, buying up used aircraft would end up as an indirect subsidy to Airbus/Boeing by preventing a flood of 2nd hand aircraft on the leasing market - not a Govt function.