Hedgehog poo looks like this (it was the first thing I noticed):
I feed mine on a mix from the rspb but I don't think it is necessary to buy a special mix. It contains suet, cranberry, peanuts, sunflower hearts and dried mealworms. I pad it out with cat biscuits if I'm getting low.
I would make a log pile in the hope it comes to live in your garden.