I would use a piece of rubber sheeting. That is what is used for bed wetting. It feels 'flannelly' on both sides so it would be gentle to your table top and you just throw it into the washer. If you want to make it pretty, just stitch a piece of PUL to the top. Neither fabric frays, so you could just stitch around the edges. (PUL is a treated fabric that feels like it has a soft laminate on one side. You often find it in the baby fabrics, Joanns carries a line called Babyville.) And, whenever I work with anything laminate or vinyl or thick, I use clips.