I put myself a training plan together last summer to target the York marathon. I'd planned 16 weeks but made it 19 weeks to allow for some easier weeks when away on holiday.
My corner of Cheshire is pretty flat, so Tuesday nights became TNT - Tuesday Night Training. Easy 1km warm up down to the local playing fields and then hill reps up/down the grass banks. I started with 6 reps up/down the longest slope, followed by 10 short, sharp reps on a much steeper slope. Some nights I would also then do pyramid sprints round the footy pitch:
Sprint 1 side, jog the next 3
Sprint 2 sides, jog 2
Sprint 3 sides, jog 1
Sprint 4 sides
Then an easy jog home again. Generally every 2nd week I would up the number of reps on the long hill until I was at 20 (ish as I'd forget how many I'd done between 10 and 15, so might have done 21 or 22!). You end up with Garmin tracks like this
I ran the
Chesterfield Half Marathon as part of my build up for York. That had some challenging climbs in it (though the course description claimed fast and flat - hmm!) but I felt very confident about going up and down the hills. The hard nights of 20 long reps were 30 to 40 minutes on the hill, so even a 1 to 2km climb (5 to 10 minutes) was well within my training. Took five minutes off my HM PB that day, even on a course much tougher than Liverpool (my previous PB).
End result was that, along with a much improved race nutrition plan, I took 47 minutes off my marathon PB in York
HTH!