I completed my training in August this year and had mine done in just under 4 weeks. That is quite a record but we were blessed with 95% decent weather.
I have heard that in the months from now until the spring that it is really weather dependent. Having said that a friend of mine in Scotland commenced his in December and was completed by February so not all that bad.
If you are worried then talk to the school, ask around and if all else fails and your not happy then delay the course.
Good luck