One thing that has been omitted from this thread is the fact that if you fly every now and then, the chances are that you'll get rusty on items previously learnt. I.e. If you do climbing and descending during one lesson, then take a month break until your next lesson, you'll most likely have forgotten everything (or simply gotten rusty) you did in the last lesson and spend half of the current lesson relearning what you did a month ago.
This works out to make the whole process a lot more time consuming as well as more expensive.
The way is to fly as often as possible, so it's all fresh in your head and makes the whole process a lot easier and cheaper. Which, as others have said, might mean waiting until you're a bit older. Try the cadets, though.