The medical school will be very supportive of you, and help you in any way they can.
I've had chronic health conditions which have affected my ability to do exams and go to placements at times, but I've been clear about it from the start, and have received a lot of support from staff.
The medical school can't help you if they don't know there's a problem. Even if you don't want any help at the moment (I refused any treatment at the start as well), it is still best to let them know. That is, once you get into medical school - you will generally have to complete a health questionnaire and attend an Occupational Health appointment so just be honest and raise any concerns you may have.
Please don't worry about things like fitness to practice just yet though. There are so many issues that students go through, yet a lot of them manage to get through them with help and support, and become doctors in the end. You'd be surprised at some of the things students have been through, I certainly was.
It sounds like you have a positive attitude and are willing to give everything a go - which is far better than my own attitude when I thought I would fail medicine and end up living on the streets.
As long as you look at your issues with a clear head, see where there could be a problem and look at the various solutions, I don't think you'll need to worry about FTP. Obviously this comes from someone who has no clue about what you are going through. But also remember that the medical school can offer adjustments if you are struggling, which also include support during placement.
For now, I would concentrate on getting into med school.