I'm not current serving having left the system some 17 years ago. Even then I only served in the PTI role for a year before digressing into other mil skills. However............
It's not correct to describe a PTI in terms of a " civvy qual " as you phrase it. PTI's undetake a series of coaching / umpire / referee qualifications under the particular sport's National standard requirements, as any "civvy" has to do. Military personnel will usually be sponsored through these courses whereas his civvy counterpart on the course(s) will be self funded.
Military PTI's have a broad exposure to the world of P. Ed. Besides the very obvious gym sessions, there's field sports, outward bound activities of water and land based specialisations as well as support to our medical rehab facility at Hedley Court.
The PTI role is as challenging academically as it is physically. The guys and girls who come from within the Services to qualify as PTI's are in the top stream of highly motivated and self determined, confident individuals. Prepare well and the very best of luck to you.
Check with an Admin officer or clerk etc. at your unit it equates to NVQ's + dependent on level in the same respect that a driver of CVR is a level 1 qualified NVQ mechanic and reme and sigs all have equivilant NVQ's city and guilds etc.