You are going to need a worksurface which is impervious to clay, and can cope with having a sharp blade pressed down on it, and scraped across the surface repeatedly. It needs to be completely smooth, rigid and texture-free.
My preference to start with would be a large flat white tile with no surface texture whatsoever – don’t do as I did and get one with a slightly wavy surface!
And unless you are going to be working in a really tiny area, don’t buy a poky little 4 inch square… you need to be able to spread out a bit. Aim for something a little bit wider than a normal ruler (so at least 30cm or 12” wide). It probably won’t cost you more than £2-3.
In my studio I have a 120x60cm sheet of toughened glass which acts as my worksurface but in practice I only use the front 15cm of it (as I’m chronically untidy and the rest of it is covered in unfinished canes and tools and bits of clay).
Toughened glass also isn’t as tough as it sounds – it is easily damaged with the edge of blades and mine is covered in gouges.