I did it! I completed week 1! But my calves hurt SO much! They hurt while running downhill but not as much while running uphill and are a bit sore now! I nearly stopped, but a comment I read kept going through my head (sorry if I have pinched it and I can't remember who said it) that the benefits of stopping early are far outweighed by the benefits of finishing!
Two days rest (and I should image quite a bit of stretching and massaging) and then I can start week 2! Yay! π