You dont learn about this game playing ranked really. Same reason what you intend to do is why. Other level 30 kids rush into ranked not knowing anything... how do you expect to learn anything from people going in not knowing anything like what your doing?
Learning is done outside the game, experience is gained inside the game. Time spent watching videos, reading guides, studying the wiki are how you learn about the game and can be done anytime before level 30.
If youre going from 30 straight into ranked, I doubt you will place high bronze. Especially if you think thats how you learn about the game. My advice would be to learn a few champs in normal draft really well (15 or more games), then play as many as you can at least one or two matches before you go in.
You wont do this though.
You will be like all the other burdens I see in matches with little clue as to what to do, and no one will have the time to explain it to you. They will just expect you to know. It will be your fault for not knowing what to do though, so their flames will be correctly directed at you when you get them. Why should you know? Because it would only take a small percentage of your time to acquire knowledge outside of the game, then bring it into the game. Combine knowledge with experience to develop skill.
Good luck I guess.