I simply replaced the top of the table supplied with our van with a piece of plywood which I tailored to be the size I wanted. I then covered this with some plasticated material from Boyes which I stapled on.
It makes a good tablecloth and is easily wipe clean. It doesn't need to match the existing furniture.
When we sell the van I'll simply put the original table top back.
I used a round wooden chopping or bread board from TKMaxx or M&S (no corners to knock into), and the local caravan shop had the standard aluminium "cup" or base to screw onto the underside (so the table needs to be solid enough to take long screws) - the standard table leg fits into this (we have 2 such legs in our MH, for the 2 tables that it comes with). This wee round table is ideal for drinks, before the big table/s is/are needed for the meal. It then travels in what we call the dog food cupboard, behind one of the seats.