Not sure how steep the angle needs to be for a normal approach in the UK, however in Canada using the flight instructor manual a normal approach is between 6 and 8 degrees anything steeper is a steep approach anything less is a shallow approach.
To work out your angle of approach draw two lines on an A4 (8 by 11) sheet of paper at 6 and 8 degrees from the corner up then when flying hold the sheet level look down the lines and you have your approach angle for a normal approach , you will see from this even if the instructor guide for the Jaa(caa) says ten degrees most of you will have been doing steep approaches as normal approaches.
Vortex ring state: aircraft descending into its own down wash
High rate of descent: greater than 3/500feet per min
Low air speed: below translational lift
Power applied: more than 20/30% power applied
If you don't have all three factors no VRS
Recovery Get airspeed altitude permiting reduce collective setting
Or autorotate
Hope this helps