I agree with Kelly, a longer lesson does help because it takes time at the beginning of the lesson, to re-adjust to the car and to 'get going' as it were.
I passed my test, first time, three weeks after my 17th birthday.
I was very proud.
I'm only telling this, because I am about to let you into the secret as to how I passed.
The secret was - whilst I only had a few lessons - I spent atleast an hour every day with my dad.
He would drive me to the middle of nowhere - (we lived in the middle of Dartmoor - so not hard !!)
or to a quiet, unused car park.
And I would sit there, going backwards and forwards, backwards and forwards.
Belong long, my clunch control wwas cool.
I was not scared to change gear etc etc - coz thats difficult - often you feel like theres too much going on- looking, indicating, changing gear, keeping your eyes on the road - etc etc-
And I had alot of the basic confidence already there.
Thus, my lessons taught me road driving and specifics - e.g. reverse parking.
There we go - it helped me.
Get a trusty friend for hours of practice.
Then, it will "click" into place, so much easier.