I think the NPPL is an excellent route - but not to get a licence quicker. The minimum requirement is 32 hours but you already have 16 and you are simply not going to complete in another 16. Realistically I think you should expect to need the same number of hours as a JAR PPL. The syllabus is near enough the same. Check out the requirements here
http://www.nppl.uk.com/Application%20Forms.htm The hours quoted are minimums and your instructor will not allow you to progress beyond your abilities.
I am about to do my qualifying X country and then final hanndling test and at present I have 45 hours logged. I am doing NPPL because I have no professional ambitions , no plans to fly abroad, no desire to fly in the dark or do IMC/IR. The bonus for me is the cheaper medical, with less frequent renewal, cheaper licence fee etc. Why pay for what you do not need. Sorry to seem negative but flying is full of setbacks, especially this year , the weather. I say just carry on with whichever course for as long as it takes but enjoy it. It is worth it.