To want to be in the CF I personally think the first step to respect the CF, that includes the good with the bad. In your situation, you have to respect that there is a minimum medical enrollment standard, plain and simple. And as has been beaten to death on these boards, the only person who can tell you that is the medical staff themselves. Statements such as "do they have a right to check my medical history" and "what if I never told them" are proof enough to me that you don't fully respect what you want to be involved in.
The answer is simple, yes they do. Not because the CF are special and need access to your information because they're out to get you, imagine it like switching GPs. Your new GP will want the files from your old GP so he knows how to treat you. Only difference here is before you switch GPs (accepted into the CF), the medical staff wants to review it. Hold it back, and you'll get caught, plain and simple, then the dream will be dead for the rest of your life.
It is not like you have a cold or the measles. Get healthy, look after yourself and work through it, that should be priority #1. Then, possibly you will be cleared down the road. I'd suggest starting the process so as to set a benchmark for how much you've improved in say 3 years time.