This is mine. An old computer desk frame which originally came from Ikea, the top is an offcut of kitchen worktop. This is protected by a full size cutting mat, I think this was 0A0 size or around 40 by 25 inches when I bought it. For actual cutting I use an A3 size cutting mat over that as can be seen. I protect the desk surface with the large cutting mat, because you are always going to have accidents. If you look at the large cutting mat the surface is terrible, twice in the last year I have knocked over a bottle of plastic solvent and it has dissolved the surface.
Its not bad enough to throw away yet, but if it had been the worktop itself it could have been ruined by now, and its cheaper to replace the cutting mat than a kitchen top. Although to be honest here in Spain I could get a perfectly flat surface made of marble, just by crossing over the road and helping myself from a disused marble cutting plant about a 100metres away. But what I have is ok for now.