There are two coding systems in common use in Private Practice.
The first is the CCSD coding system. It is owned and managed by a group of insurance companies who regularly update the codes. Click on https://www.ccsd.org.uk/ccsdschedule/ccsdschedulechapter/ to find out more.
The second is for NHS work performed in a Private Hospital. It is the HRG coding system, and is usually administered by the Hospitals themselves.