When I started my NPPL it took longer than anticipated , work , family and life gets in the way unless you are very lucky.
Get your majority of flying hours in first , pass your Air Law before you go on your first solo , and dont do the other written exams until you are getting near to your skills test , especially if it's all dragging out over a long period of time. Make sure you've passed your Nav before you start attempting to go cross country solo student , make sure you are happy with the whole Navigation requirement.
I did all my exams relatively early , especially when the weather precluded training , only problem was I had more and more crap weather before I achieved enough hours to carry out my GST , I then decided to spend a relative short time committed to intense flying , had to re do a couple of exams which would have lapsed just prior to sending off my licence application due to the time taken to complete the whole syllabus.
Make sure you do all elements of radio exam practical and written more or less at the same time so that one half doesn't run out.
Learning to fly isn't a race .... enjoy it , no matter how long it takes
