yes, you 'can' issues as much money as you 'want'. no, you cannot ignore markets completely, because the UK government also borrows on the bond markets and government debt interest payments is 8% of public spending and can spike higher.

Gilt sales serve a useful purpose in the economy providing a very secure way to park some cash but the govt does not need to borrow to spend. Bonds can only ever act as a kind of secondary buffer, soaking up £ as the buffer size increases, releasing £ when it shrinks.

If, and only if, the government sometimes runs a surplus and pays some debt down. If a country consistently runs a deficit then it means printing or borrowing. The last budget surplus in the UK was 25 years ago.

Quantitative tightening is currently reducing the size of the national debt (although not by much and it may not last). Another aspect of running a deficit is that it may simply be an accounting record of economic growth with no adverse impact. We need more credit & new money for this.

You could ignore the gilt market in isolation, though. His point is you could pay back every penny of debt tomorrow by ordering the Bank of England to print money. No debt, no 8%, no interest payments. The problem if you did that, under normal circumstances, would be the currency market...

Govt definitely needs to have a sane plan if it's planning a deficit ie a strong prospect of growth to absorb all the new money without inflation problems. Given that, traders will have to think very carefully. Can't afford to make bad bets.