I'm just at the end of my PPL training (cancelled three skills tests already this week due to weather, aaaaaaaaaaaarghh....
) and would absolutely recommend saving up and just doing it full on. It took me three months to do my required hours, I wouldn't have liked the thought of doing it a couple of hours a month, what you need is continuity.
Get the exams out of the way ASAP as you always think that you have plenty of time to do them; the reality is that your skills test will creep up pretty quick and you find yourself with two or three exams outstanding which you then have to cram in. Also do your medical first, it's pointless starting until you have that. The first exam to do is Air Law, doesn't really matter what order you do the rest in.
I know you probably are itching to get started but I can't stress enough how much better off you will be if you just save up the loot first and put it to one side. Good luck!
Incidentally as far as weather goes I've had more weather cancellations this month than any other, it doesn't follow that winter will be a bad time to start. I believe a guy did his PPL in two weeks last November at a club in Wales.