Here are some links for you to find out more about this subject, from writers more qualified than me! Several are from the USA, or some from Australia, but the information applies almost exactly to the UK, as those countries have the very same type of own-currency economies. Just read £ instead of $ or A$.
Mike Hall. Based in Eire, authority on MMT: https://www.facebook.com/MMTforRealProgressives/
From the USA, but applies equally here:https://www.realprogressivesusa.com/news/post/2018-09-10-mmt-basics?fbclid=IwAR2tt5G155SWP5lwoH1WCHEaIegj0PbBmpGzEzo97QLgY5qSb9sG6HWvVQc
Great interview with Warren Mosler, the father of MMT https://www.realvision.com/theor-vs-practice-the-father-of-MMT-on-policy-profits-and-politics?fbclid=IwAR3fxgrXh6Acuo9xuHGsWVPWcjGkVr-GJkt0jQuBPm-q7vMdKwUdxbey9Ek
Professor Bill Mitchell, a leading authority on MMT: http://bilbo.economicoutlook.net/blog/?p=39928&fbclid=IwAR0EWixCQNtwWEH-bA4zQXD726URN61FmNgThzitlVc7biMNidbg0c0WWH0 picture-myself with Professor Mitchell, September 2019, Brighton,
UKs leading modern money studies group: https://gimms.org.uk/