The book was probably written in the 60-70s, and I think I read it in the mid-1980s. The story from what I can recall was that of a man who went forward in time while he was in the confines of his room. He was sat in his chair and when he stood he turned to see his decayed corpse still sitting in the chair. Later in the book there where creatures who came out of a hole in his garden who resembled those from H.G. Wells's time machine. I think the book was more of a novella and it was first person narrative like he was writing a diary.