In reply to Wibble Wibble (and marie):
Sorry I didn't mean dont train at all, I meant dont worry over much about the training because it is still enjoyable running round the fells for two days with a mate no matter how fit you are/how well you do. What was it that person said, the best x y or z is the one who is having the most fun.
Agreed about the terrain. One year all the contours went one way and a I knackered the outside of my right ankle good and proper, so train on contours (especially with no paths as that is what you will be doing alot of)
Take your point about your knees marie,I would reccomend some sorbothane insoles for your shoes and get some inov8 shoes as they have more cushioning. also try to run off! paths whenever you can as the grass on the side will be better for your knees I would have thought.