Is a driving school or instructor's pass rate important?
The driving school or instructor's pass rate isn't always everything. You'll need to be aware of the context surrounding any figures you're given.
An instructor could have a 100% pass rate, but if they've only had one student, it's kind of pointless. Similarly, if a driving school takes all its passes into consideration, its likely they'll all have pretty good pass rates. Perhaps a better question to ask might be 'how many people passed first, second or third time?'
The most important thing about your instructor and driving school is that they give you the support you need in order to learn to drive. Remember that it's you who's paying them, so you need to be comfortable with your progress and the teaching.
When will I be ready to take my test?
Regardless of who teaches you, it typically takes 40-50 lessons (costing around £24 per hour with a professional instructor) and around 22 hours of extra practise to pass your test, on average. So grab any opportunities you can to get out onto the roads with friends or relatives, in addition to your lessons, to make sure you have the highest chance of passing your test without a hitch. Statistics show that less than half of prospective drivers in the UK (47%, to be exact) actually manage to do so.