There are 101 ways to go about doing a PPL, everyone is different. To me, it seems like a sensible way of doing things. You can do the studying in your lunch break, on the train / bus home, whilst eating dinner etc etc so is far more flexible.
Taking a few weeks off (providing your school has the availability of aircraft and instructors) in good weather is a good idea to get the flying side of things done. I'm assuming you're in the UK, so you know the nature of the weather. The fact that it might still hose down with rain is less likely, but not impossible.
Good luck!