I agree with Andy, there is a lot to be said for having multiple instructors from the point of veiw of gaining experience. You may even find that different styles of instruction suit different bits of you tuition (presumably you start your navigation soon)
Beware though, being too keen to fly might mean you fly with too many instructors. I made this mistake with a well known London flying school once upon a time, I think I five different instructors in 11 sorties. Some of these sessions were completely valueless because of the lack of familiarity between myself and those instructors who had never flown with me.
Another thing, make sure that the instructors involved talk to each other before you fly, there is no point in you flying an exercise with one instructor that you have already flown with another!
