It is generally not recommended that you any undertake any locum work during your GP training. This link to the Sheffield GP training scheme page has much more information about what steps you should take if you do wish to undertake a locum shift whilst a GP trainee.
The COGPED paper relating to OOHs can be found using this link https://www.cogped.org.uk/publications/cogped-out-of-hours-position-paper.html. Page 12 has the following statement:
“this is likely to require an indicative benchmark of a four to six hour session every four weeks adjusted in other settings on a pro rata basis”
This would suggest that whilst in General Practice you will need to undertake one session per month of between 4 and 6 hours. This would equate to 18 sessions in total. It is important to note that the aim is for you to acquire the necessary competencies in OOHs, not just the minimum hours.
Currently all GP trainees must do an audit/review of a QOF area before the end of their training. There is a move that this will change into completing a Quality Improvement project. Quality improvement projects can take many forms. The document linked here file:///C:/Users/User/Downloads/wpba-QIP-practical-guidance-for-trainees-250416.pdf is on the RCGP website and describes in more detail what a quality improvement is and how you might complete one.