Hog holes are one of the things which can be logged on the Big Hedgehog Map. So you should be able to zoom in and find those which have already been logged in your local area. But you could encourage more people in your area to add any hog holes to the Hog Map, too.
There also seems to be something you can click on, if you follow the link given to the ‘invitation’. I don’t have the right hardware for that – smart phones, I suspect – so not sure where it takes you.
But it seems a great idea to encourage people to make more hog holes – apart from anything else, that way hogs also have less need to cross roads to find suitable habitat – which alone makes it worthwhile.