In case it helps...
The UK GDPR states what a ROPA needs to have in it.
https://www.legislation.gov.uk/eur/2016/679/article/30
The ICO makes a distinction between ROPA requirements and ROPA good practice.
https://ico.org.uk/for-organisations/uk-gdpr-guidance-and-resources/accountability-and-governance/accountability-framework/records-of-processing-and-lawful-basis/#Good-practice
You may wish to consider what information beyond the statutory items would be useful to you e.g. you could have a risk rating where items containing child and/or special category data are considered high risk and therefore require extra care.