AIC 127/1999 was withdrawn by the CAA as certain Instructors were using it as if they were conducting a skill test on candidates.
The training flight is not a skills test. Training COM 1/2006 contained advice for instructors concerning the flight. It states that:
'Instructors are reminded that the primary aim of this flight is to ensure safety. In addition it is an opportunity for pilots to:
Brush up on existing skills and knowledge
Revise infrequently flown exercises
Possibly learn something new.
As Examiners we are also reminded of this in Standards Doc 14 V5.
So to answer your question, anything that you want maybe covered in your 2 year flight with an Instructor. If you are lacking ideas then the areas above may be suggested by your Instructor.
Try something new, tailwheel or differences training or just refresh some skills. The world is your oyster!