To add to what Wildlifehaven said, the following are some links which you might find useful.
If your garden is very big and has internal fences or walls, you might like to make holes for the hogs to get through to make it easier to get around. Also if there are any raised areas, maybe make some sort of ramp or steps. They are quite good climbers, but if they are in a hurry looking for food, may welcome an easier route. Make sure there is an easy exit route from any pond.
There was a survey on hedgehogs homes last year and I believe the results are due out fairly soon, so that might give you more information about the best places to site a hog house – maybe for when you get the next one!
Good luck and happy hog watching!