You need a PPL to fly an aircraft in this country.
Flights with military pilots, and thereby also your mates air experience flights, don't give you any hours towards your PPL unless the pilot is also a civilian rated instructor. Neither will your TMG unless you were PIC (which you'd only have been on your solo flight) and even then I believe you can only claim 10% of the time.
I'm afraid that in the eyes of civil aviation, you are no different to someone with no flying experience. Only your friends UAS time will count (as I believe that's under civilian rated instructors towards PPLs) but with the experience he's gained he could relatively easily "finish" his PPL with a flying school and then hire the plane.