Presumably you are looking for a document relating to guidance on teaching. There used to be a document CAP528 Commercial Flying Instructors Guide. This was last produced in 1987 and was withdrawn around 1995. Whilst a few copies still exist, it has never been replaced with any other document.
CAA Staff Examiners usually have a copy of Instructional Techniques for the Flight Instructor by Alan Newton, John Halstead
(ISBN 0-9542751-0-1)
ONTRACK AVIATION LIMITED