The CDI has produced an observation framework specific to IAG which if you haven’t already seen might be useful.
The framework is for the use of all career development professionals who carry out one-to-one interventions with clients. It has been developed principally for use with those professionals who work with young people in school/college but can also be used to assess the quality of interventions with other types of client.
It is particularly useful for those professionals who are working in schools/colleges who hold or are working towards the Quality in Careers Standard (QiCS), where quality checks of interventions is a requirement, and especially if the practitioner is self-employed or is employed directly by the school/college and is therefore not subject to quality checks already by their employer.
Other resources from CDI that are useful are how you can use the National Occupational Standards to develop documents such as job descriptions, review frameworks etc: