Certified Plumbing Contractor in Florida can license (qualify) a plumbing company, pull permits, run jobs, basically anything necessary to run a plumbing business.
You can't take the test until you're approved to do so. You'll have to submit your application showing all relevant experience, copies of W-2's, etc. in order to get a seat at the exam. You'll need all the books on the list, with no notes or underlining, for the exam. They will check them before the exam starts. You will need to show experience in all the required areas. If you don't have experience in every area documented on you application, you won't get approved to take the exam.
I passed on my first try, many don't. I'm a book nerd and have always been good at tests, so it was easy for me. I didn't take a course, I just read all the books over & over.
Honestly if you have as little experience as you say you do, you've got no business taking the exam.