Hi, your uni should have documents that will explain the marking criteria, but yes, it is strict and certainly not easy to get a distinction. Your marks are really good, I found that my dissertation mark wasn't far off what my main marks were, I averaged 74 and my distinction was a 75 so it may well be that you get the 70 you need (I'm guessing its a 70 if its the same as the marking scheme at my uni). Is it long until you hear? I submitted Sept 15th (oh, its a year ago tomorrow - what a difference a year makes lol) and heard mid December. I do hope they don't keep you hanging on as long as that!