So if you are going for the full PPL, you need to give some thought to which jurisdiction you want to do it in. If you do a Netherlands licence, that is valid throughout the EU, but it's not valid in the UK or the USA. There are schools that will do UK+EASA (European Aviation Safety Agency) licences side by side, and it's easy enough as both the flying and theoretical knowledge syllabi are basically identical (the reasons for the split are political, and frankly not worth worrying about, they just are).
If you want to take the exams in English then your obvious countries are Ireland or Malta, both of which have a good reputation as aeronautically sensible places. I'd look to schools there, and maybe Spain (Fly In Spain in Jerez is one I happen to know that do UK and EASA side-by-side) who can arrange the exams and flying training this way. (I'm guessing you're a British citizen or joint citizen, if that's incorrect say, and I'll provide some further explanation). That way you can study once, just take two sets of very similar exams, one flight test with a joint rated examiner and get two licences.
I would certainly recommend starting the theoretical study now - find a suitable groundschool provider and get signed up with a correspondence course. Look to where and when to do your flying training however: you probably don't want to get constrained to only being able to fly in the EU if your nationality isn't an EU one.
Assuming that, say, you can talk your family into a holiday in the right place, you could probably do the full PPL course in 4-5 weeks - wrapped around your 17th birthday would be the ideal period if you have the patience to wait a bit. The issue with doing it slowly, for you, may be doing it in the Netherlands, but so far as I know there are no schools there who can train for anything but EASA licences.
G