I am in the same groove as Mad Jock, as an instructor there are a fair few variables.
Quite a few people seem to get hung up on how many hours it took them to go solo, but to be honest, it really is not important.
When people suggest they went solo in 7 or 8 hours in a bragging fashion, I would always ask the question, how thoroughly were the lessons taught? You have to remember that exercise 12 and 13 are circuits. From my own experience, students would solo anything from 10 hours to 30 hours. If you have a student that flies every day, and is lucky with the weather, they will solo far quicker than someone who flies once a week, and is unlucky with the weather.
In terms of your stratergy for the rest of the course, I would try to be ahead of the game. Read the books, get your instructor to brief lessons on rainy days and take everything on board and really prepare for those lessons. It will make it so much easier for you, when you come to fly the detail.
With regard to your question about how long it takes to complete a PPL, it depends on the individual. I have seen 3 months to 2 years. It all depends on the person, learning ability, commitment, flying frequency, natural ability, and the list goes on.
Dont get too hung up on the above, just enjoy it, its such good fun.
All the best and enjoy your course.
CAT 3C.