If I started my NPPL training, and then did those 10 hours training, could I, theoretically, when i'm 17, do a few more hours and gain my PPL?
Yes. But one thing to watch out for is the effect of the wretched €urocrats and their pointless and unnecessary LAPL. Although there should be a 3 year transition period before this nonsense is introduced in the UK, there is no guarantee that the CAA won't repeat the mistake it made with JAR-FCL and try to introduce it in 2012.
Industry has a lot of flexibility when agreeing NPPL credits and waivers; however, when the leaden hand of €urocracy is forced upon us, that will probably cease.......