similarly not all students pick it up as quickly as others, some need practice. some students can be stuck on circuits for longer than others, as the approach and landing is one of the most if not the most important part of the flight.
chas - stick with it mate. i became totally comfortable with flying after about 10 hours. since then it's been excellent. enjoyed every minute of it. you will love pottering around the sky, doing stalls, circuits, landings (my favourite bit), and then navigations, which are really good. navigating and landing away is when you feel your training comes together towards this end result.
stick with it, you will enjoy it. don't let turbulence and all that put you off, some days you will fly around and it will be smooth as silk and you will think, there really is nothing better than this.