Witchfinder: The Last Nightfall by William Hussey
With a sickening jolt, Jake realized that everything before this had been just a prelude to terror. Now he could see and hear the darkness of demonkind. Now he had reached the Shore of Damnation. Now he had truly entered Hell ...The Demon Father has taken control of the United Kingdom. He is on a mission to open the door to the demon realm, destroying all of humankind. Jake would go to hell and back to stop him ...but will that be enough?