For JAR-FCL purposes, Air Cadet 'Air Experience' flying is considered to be passenger flying, albeit very interesting passenger flying. It is not considered to be flight instruction.
However, a flying scholarship flown with civil flight instructors may be counted in full.
Your Vigilant time will count towards a PPL with TMG Class Rating, but only 10% of PIC time (up to a maximum credit of 10 hours) on the Vigilant may be counted towards other Class Ratings.
Also look at
http://www.nationalprivatepilotslice...20REV%2008.pdf which outlines credit available towards the UK NPPL.