If you can't find normal wood sand paper then the emery paper should fine to finish off the smoothing off of the cricket bat. You may need to do a bit more sanding to get it smooth as the grit will be very different from normal wood sand paper. Remember you are dealing with Willow, so you shouldn't be able to damage the bat badly at all if the emery paper does not work.
What are you wanting to actually do with the bat?
Have you oiled the face of the bat yet?