You can buy materials specifically designed for worktop repair even from B&Q. Fablon is ok to cover a shelf or drawer bottom i.e a single surface. If your worktop has a vertical front edge though it is almost impossible to wrap around the sharp edge satisfactorily - the Fablon has a tendency to retain a radius, so this finish doesn't look professional. Its also not durable enough as a worktop surface.
There is another approach I have used too: I had a damaged surface over a chest of drawers, rather than the main one in the kitchen, so simply unscrewed it from the cabinet. Measure in 2 dimensions where the damage is, then turn over and mark the location on the underside. Use a hole saw to cut the bottom layer away, then cut away the bits of cardboard honeycomb, to reveal the damage. See if you can press it back into shape, but it will probably spring back. So, add some original Araldite to the underside of the damage, then a small wood block, finally clamping through the hole and block to a a flat surface and leave overnight to set. No need to bother with the hole which won't be seen...