If you are going to buy a $30,000 CNC router to build your design, you might want to use something else. If you just want to build one set of end tables and nothing else, ever, then just use a pen and pencil. If you enjoy using your computer to do stuff, or, are planing on building more stuff and making more drawings, then, SU is worth spending a few weeks learning to use.
It took me 3, maybe 4 tries before I got a good handle on it's basic use, so I probably have at least several weeks in learning the program.(over a period of several months) It is ,imnsho, not that easy to learn. It IS easy to use once you learn the basics.. You could draw up, and build your two end tables much quicker than learning the basics of SU. On the other hand, once you get the basics down, you can have a ball using your computer to make fantastic, detailed sketches of anything normally built in a home or smallish cabinet shop.
Personally, one of the main reasons my wood shop has not been busy in the past 20 years is I started screwing around with computers, initially I wanted to make cad drawings, and got a copy of Design Cad sometime in the 80's. Spent a few weeks learning it, drew up a barn in a week or two and built it. I could have drawn up the barn on paper and built the thing in much less time than it took me to learn design cad and draw the thing up on my PC XT. Then, I discovered that programing was almost identical to woodworking, in that you could create/build stuff (applications) that did stuff but mistakes were fixed with a few button clicks. My shop fell idle and a new, just as rewarding hobby took over. Now, I'm trying to get back into woodworking, but alas, still have trouble getting past the SU phase of projects.