I had probably 55-60 hours.
I had about 35 hours with two different instructors and I just was getting nowhere. Then I rode bikes for over two years on the road, got some lessons with an instructor friend of my dad's who does road instruction as well as track stuff, and I probably had 16 hours or so with him. Found it much much easier.
I think it was a combination of the instructor being very good imo, and obviously I had a huge amount more road sense and so on from the bike. I struggled so much before, but I don't think I really *wanted* to drive at that point (like reeeeally want) so I was probably hard to teach. Much less confident then as well.
The first and second instructors I think were £18-20, the last one my dad's mate was £20.