Long runs with alternating hills?

[SkiMonday]

I'm trying to figure out how to fit in some hill training and some easy long runs. I've got a run of about 20k which has plenty of hills, trouble is the first (and therefore last) 5k is flat so my hill run becomes my long run. Also, I don't want to drive there. It seems that a gentle long run is important for building endurance so I'm thinking of alternating weeks between flat and hilly.

Does this seem reasonable? Would I be better off doing a hilly run every week? I've still got over three months until my HM so there's plenty of time.

[roseabi Ultramarathon]

Sounds like a great idea! If you like you could include a short intervals session on your non-hilly week for similar gains. And if you take the flat 5K parts of the hilly run nice and easy that will contribute to your total weekly gentle running.