Stickshaker:
I think just about everyone thinks the same as you do, before they start flying, "How long will it take?" An extension of that is "How long before I can fly by myself and be free of the instructor?". Like you, at first I viewed flying instructors like all other teachers in my life, that is, they would teach me what I needed to know, spank me on the bum and set me FREE! With flying instructors, it's different and it should be. You never stop learning to fly and the instructors are a lifelong reference (or should be), rather than just teacher / assessor.
Although I don't fly with my instructors much anymore, I still contact them from time to time with questions and more importantly, I still regard them as friends. The last bit is the important part.
You should find and instructor that suits your needs and personality, rather than just being geographically convenient. You will spend a fair amount of very high intensity time with these people and if one of them rubs you up the wrong way, it will not only hinder your progress, it will poison your mind to flying and flying instruction. From bitter personal experience, I had an instructor in Canberra many years ago who was so bad, he put me off learning to fly for 20 years as I just assumed they all behaved like he did. To be honest, he behaved much like my Little League baseball coaches did when I was a kid which was just shout and criticise.
Do yourself a favour. If you get out of the cockpit feeling stressed and negative, something is wrong. Try another instructor.