when i learnt i had a lesson a week, probably half were 2hr lessons. I started in the october and took my test in the january, so expect i had about 25-30 hours.
my friends son did the theory first before he even booked driving lessons, once he passed he started having practical lessons, he said this worked well.
Sara, I went with a independent instructor. After about 4 weeks he told me to put in for my test as by the time it came through I'd be ready. I think with some of the bigger firms it's just business and they want you to take as many lessons as poss.