Professor Stephanie Kelton explains in words we can all understand why it is that a government with its own currency can never run out of it.  A sovereign government can not run out of dollars or pounds or kroner in the same way that a joiner can't run out of inches or a football team can't run out of points.  Therefore the Westminster government's austerity is a political choice, not an economic imperative!
https://www.youtube.com/watch?v=WS9nP-BKa3M&t=135&feature=youtu.be&app=desktop