PPL
I started my PPL in late November (i.e. last day) 2006, completing early August (2nd?) 2007. I flew once or twice a week, but did take a week off work and flew every day for 9 days. I reckon if you went full time (there are full time FTOs out there) you could get it done in the UK easily in that time. Unless, of course, you really have no aptitude for flying and struggle.
Also my log book shows quite clearly that, personally over the 2 years I've been flying, I get more flying done in the winter, than I do in the summer. That is just what I've experienced though, individual results may vary, the value of investments can go up as well as down etc etc