why has it taken everyone so long? this OP is learning over summer, so they will probably have lots of free time to have driving lessons. theres nothing wrong with booking two hours a day for a month.
I think that is long enough, and i dont know what it is with people having so many lessons, most people i know had 20 maximum, most under 10 lessons.
If you get the theory out of the way a few days after you are 17, then assume a small waiting list for the practical, and just cram in a bunch of lessons, even if you are not insured on a car of your parents to learn in, there is nothing wrong with going to a carpark when it is not in use. and practising the manouveres and stuff.
OP i think it is easily acheivable, good luck.