CSE3660 - How the conditions are to be interpreted: Exempt and/or non-business activities: What are exempt supplies?
You should check the other guidance available on GOV.UK from HMRC as Brexit updates to those pages are being prioritised before manuals.
The exemption for CSG services is only available to entities that make exempt supplies under ‘public interest’ activities. This covers any supplies falling within Groups 3, 6, 7, 9, 10, 12 and 13 of Schedule 9 of the VAT Act 1994.
It does not include supplies under other exemptions such as insurance, finance, betting and gaming and land nor those with the right to recovery, for example because they are specified exempt supplies.