Children Book Illustration Research|PPP3

For some time I've been wondering what it is I exactly want to do. Is it concept art? Animation? Illustration? Comics? A very difficult question, which I'm unable to answer at this point. However, as I'm still trying to find myself, I've decided to look at one of the options.
Illustrating children's books been a dream and one of the personal goals for the long time. To be honest, opportunity to illustrate any type of book would be awesome. However, children's books are able to offer more creative freedom than regular title aimed at adults. Usually, when it comes to books, it's only a cover images plus few illustrations inside. Reader treats them as extra, a nice treat. But when it comes to kids, they look at those images as inspiration to let their own imagination go wild. The goal is to enrich their imagination. And since so many books are for children that haven't mastered reading yet, illustrations have to tell the story.
Another goal in this field would be for me not only to be able to illustrate somebody else story, but work and publish my own. Ever since Alice appeared in my life, the amount of stories that wonder in my head increased dramatically and I've got this constant urge to share them with the world. But how do you approach this task? How do you get in touch with publisher or agent, make a pitch?
I've been following Will Terry's YouTube channel for quite a bit time. He is a professional children's book illustrator (and teacher) with many years of experience. Recently he launched a new series on his YouTube channel in which he's discussing his journey of publishing book.
I want to also note that at the time I'm writing this blog post, Will haven't published it. We, viewers rooting for his success, don't know if the story'll be a hit or not. One of the illustration he shared looks very good and I'd love to see it.
My plan is to learn as much as I can from his experience. I'm aware that publishing an actual book is very difficult task and in my case it could be a bit easier to get it out by making it digital, in form of app. But before I start on that I need to create a decent story, design characters and enviroments, establish mood and art style. A lot of work ahead, but that's very exciting.