Well, I'm a bit late posting my week 5 summary, but it would have to be the best week of training so far. All 4 runs got done, 2x5km, 1x8km and 1x10km, and they all got done in good times. The 10km run was done at 6min 35 sec / km, which is about 10sec/km faster than any of my earlier long (or medium length for that matter) runs. I also felt nice and comfortable doing it, and would have been happy to carry on at the same pace for longer. I followed that up with a 5km the next day, that knocked a minute off my previous best time for that track.
So all in all, a satisfying week. I'm starting to feel as if I'm making progress, the fitness levels are going up, and the long races I have planned for the next few months are starting to look more achievable.