As FW says, an ab initio student will probably need somewhere between 60 and 70 hours before being up to the standard required to pass the exams. I'd budget for 65 hours (£16k inc VAT at those rates, plus overheads - course materials, exam fees, medical, etc.), but remember there are lots of students that have taken more than 70 hours (sometimes a LOT more!)
Usually the students that go over 70 hrs are well BELOW AVERAGE. I know a lot of people who have got their license with minimum hours or just over them. But yes, dont be more focused on minimums over quality of training.