Thank you so much for your helpful replies. I do agree with a part melee/ranged champion not being so great for my transition, because I know I will just stay in ranged mode where I'm comfortable! I think I'll just need practice, practice, practice. I want to trial a few different melee champions, tanky, assassin and bruiser/all-rounder. One other question I had: Where is the best lane to practice this more? I know most of these champions live in top lane and jungle. I have tried a few melee supports but their mechanics are a little different. So top or jungle? (Some at mid too).
I trialed a couple of games with Kha'zix, I love the way he works, and out of all the melees I have attempted (usually I play one game, get chicken and stop) I like his play style the most so far. So perhaps I will learn more with him. I like his kit.