Desk/bench design

I was looking through some of the projects for an idea to build a gift for a little girl that I know very well that has Down’s syndrome. I came across a project that was a bench with a desk. She is turning 5 this April, what a great idea!

A couple questions I have. I am in the rough design of the project and I had some ideas:

Have a solid slab for the desk and the bench top or just use regular lumber. If it’s possible I want to stay away from plywood. I want to make it a little fancier because she is special to me. Is it possible to use dovetail jointery on boards that are glued together to make a solid wide board? I’m worried about doing it that way because of warpage.

Otherwise I was wondering if it’s possible to dovetail maple or oak plywood or something to that type. I haven’t worked with that type of plywood much so I’m not sure what my options are. It has to be relatively light so it can be moved around; I was thinking about installing wheels underneath that are hidden so it can skoot across the carpet.