As one who is not far beyond newbie status myself, I'd go with pine, rather than oak. Pine is easier to work with, and yes, it's softer, but there's a lot of furniture (e.g. Early American style) made from pine. It's also lighter, but the design you posted looks substantial enough that made from pine it should be plenty hefty.
As a newbie and recent newbie, I always make mistakes- it's easier for me to accept and redo mistakes in cheaper wood than the expensive stuff, so for that reason alone, I'd go with pine. If this project is a big step forward for you, use it as a learning experience. If you like the results in pine, and want to move up to oak, you could sell or donate the pine unit, and use the skills you learned for the next project.
BTW, if you decide to go with oak, your money would be better spent on a tool other than a biscuit joiner. Yes, it makes it easier to line up boards for a slab top, but reasonably careful attention to clamping provides the same results. If you don't have them already, a jointer and thickness planer would be much more useful tools for this project. Just my .02 Good luck!