The idea that a country with its own currency cannot become bankrupt is demonstrable nonsense.
It has been pushed by the left for some years now and was a response, in this country at least, to heavy tory cuts.
You cannot print money (or sell assets) indefinitely as the currency becomes debauched and worthless. Markets will not accept it and you cannot then pay for imports. You are bankrupt.
Zimbabwe provides a modern example. The Zim dollar fell to one millionth of its launch value and was abandoned. Zim internal transactions had to be in scarce foreign currency such as the euro. The value of the Zim dollar was less than the cost of printing it and the piles of notes became useful only as doorstops.
Eventually Zimbabwe launched a new Zim dollar. How that has fared, I'm not sure.
UPDATE
The latest version of the Zim dollar was subject to an inflation rate of 350% p.a. as at Jan this year. The government holds auctions of foreign currency each week, so transactions are more stable.