'Ello.
Welcome to the world of square-eyes, bashing the screen with a hammer, getting wound up at the slightest hint that someone doesn't agree with you, no social life, wasted work time, addiction and rye smiles when you get away with posting some vaguely rude comment.
Its bloody great, this pprune thing!!!
The NPPL is a great marketing tool to get people into the world of GA. Its not much more in practice.
The exams you'll take are JAR ones, the instructors that you will have are JAR ones (at the moment, at least) The course layout, although covering less MINIMUM hours than JAR, is almost identical.
As you do not have to declare which one you're doing when you start, keep you're options open.
Chances are, it will take you close on 45 hours to learn to fly safely and properly. May as well have the JAR one then in case you do want to fly in Europe or do Night or IMC ratings etc (not currently available under NPPL).
If if it takes you 40 hours to learn to fly, only thirty of them will be allowed against upgrading from NPPL to a JAR licence. Better to get five hours out of the way now than fifteen (or more, if you've developed bad habits) in a years time.
The only people I know who are specifically doing NPPL are those who can get the required DVLA HGV medical but not a JAR class 2 medical for a JAR-PPL. There are some stupid reasons why you can't get a JAR medical, but some good ones aswell.
If the medical criteria applies to you, think carefully about what exactly is wrong with you. You may be able to get an NPPL, but you still have to pass a check flight and the scrutiny of any club you may want to rent aircraft from.