Leave your tabletop longer than necessary until the sanding is done, then cut to final length. Most tabletops are too wide to trim on a tablesaw, even with a crosscut sled, and this is where I use a hand-held circular saw. Clamp a guide strip so it’s square to one edge, then follow it with your saw. Repeat the process on the other end, then carefully use your hand-held belt sander to remove any blade marks on edges. It sounds like a coarse process, but you can get great results this way.
Consider building your tabletop out of boards about 6" wide (1x6 or 2x6), or close in size (I use x4 and x8 boards on occasion). If you go smaller, you'll be adding more joints, which means more pocket holes and more sanding. If you go with a wider board, the board itself may cup over time, creating high and low points on your tabletop. I personally find x6 boards to be that happy medium.
Rolled-on poly looks terrible at first, but the bubbles disappear in minutes, leaving a smoother surface than most of us can achieve with a brush. Beware of ridges formed by the edges of the roller and humps where you start and stop. You can minimize both of those flaws by applying lighter coats. We experimented with several kinds of rollers and got the best results with microfiber mini rollers. We also tried rolling on water-based poly; don’t do it.
Building a table is one of the most deceptively simple woodworking projects going. What could be easier than gluing up a few boards and applying a finish, right? But reality is often surprising, because building a top for that table can go wrong in ways you might not realize until it’s too late. Here are my favourite tabletop construction tips, plus advice on how to avoid trouble.