A few things:
Costs. If you are worried about costs, I'm not sure that I would have picked ATP in the first place. It can be done for much cheaper at a local FBO under part 61 in a 152 or a champ and transitioning to complex/multi down the line. Does ATP accept the GI bill? Are you using the GI bill? Do you have the GI bill? If you have it, you NEED to use it. Going into this job with any amount of debt for just your ratings will greatly affect your overall perception of this industry.
Instructors. If you don't feel that the instruction style is working with you, you need to talk to the instructor and/or school. If that does not solve your problem, you'll need a new instructor. YOU are the customer and are spending a great deal of money for a "product." I would accept no less than an ideal fit for you in both how you learn and your personality. With that being said, be flexible to a certain extent and open to new ideas. They are the expert (somewhat) at what they are doing, not you.
Test taking. It is what it is. If you do not feel ready, then you should not take a test, any test for that matter whether it be a written or practical. Failures (multiple or a pattern) could greatly affect your hire-ability down the line. With that being said. Professional aviation is not for everyone. We are "tested" when it matters the most and you don't get to pick those times. If you have problems with the tests (there will be MANY) how will you perform when you are tested out on the line someday in the left seat or with a new student who is panicking?
Have fun and enjoy the ride. It may not seem like it but there is A LOT of fun in the A-B of getting your ratings. Don't let that pass you by.