You can certainly fly in controlled airspace with an NPPL. You just can't fly at night or overseas, or add an IMC to it. As for the hours requirement, if you're an average student there's probably little difference in reality as to how long it'll take you. Which just leaves the medical requirements being different.
The trouble with thinking it all out in advance is that flying changes you. What you think you want now may not be what you want after a trial lesson, and not at all what you want after you've got your PPL. There's a fair number of us on here who just started out to see what flying was like, liked it and got a PPL, then liked it so much we considered - and went for - a change of career. So unless you know for certain that won't happen, it's worth keeping your options open. Which might mean going for a PPL rather than the NPPL, though I think you can upgrade later if you want...not quite sure about that.