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Yes, university lecturers in the UK can be paid well.
To become a lecturer in the UK, you need a good degree pass (first class or upper second class) in the subject you want to teach, as well as a postgraduate master's or PhD qualification (or be working towards one). It's also common to have had academic work published.
Yes, it can be difficult to get a job as a lecturer in the UK due to fierce competition and the need to often take on temporary contracts.