How many driving lessons should I take?

I cannot tell you how many driving lessons it would take to pass your test because everyone is different, but I can give you some good advice: 
 
I would advise 3-4 driving lessons early on to establish good clutch control and basic driving skills, after this time I would spread your driving lessons out to maybe one for every 15 hours driving experience in your log book.
 
This firstly builds up the 30 hours for 10 in your log book that you get with an accredited driving instructor and gives you a nicely spread out growth, it means bad habits can be squashed before they become too ingrained and time to develop individual techniques is given.
 
The driving instructor can teach you a new skill in the driving lesson, you can then go away and gain the confidence at doing it, and the driving instructor can then tidy it up at the next driving lesson and teach a new manoeuvre.
 
Then finally 1 driving lesson in the week of your test date and 1 immediately before the test. These driving lessons allow the driving instructor to go through everything again making sure all bad driving habits are gone and you are performing the skills to the standard of the Driving Test.
 
This totals 12 lessons.
 
Some driving instructors seem to recommend weekly lessons, this is expensive to keep up throughout the 100 hours you need to accumulate and if you only take 10 at the beginning then this gives you a good start but bad habits are easy to develop over following months, once ingrained these habits are hard to get rid of and could cause you to fail the driving test.