Hello Jaap,
To answer your questions, yes you can now apply even at the grand old age of 32, although if you decide, the sooner the better, 'cos it can take about 2 years to hit the streets. And yes, you can go for a Commission thereafter too, although there are only 5 or so per year for Loadie.
WSop has its merits I'm sure, and when I think of some I'll get back to you. Admin(Trg)? Not a bad job, with my limited knowledge. It depends whether you want to:
a. Fly.. .b. Have a brilliant (most of the) time.. .c. Go operational.. .d. Take the risk of going onto VC-10's as chief dolly.
Etc...
It is a great job in my opinion, but you won't be CinC, and if your heart is set on being a Zero, think deep. As has been said, do contact the Boys on the Sqns - ask for the Deputy Loadmaster/Crewman Leader. All the very best.
Gabe