Trentsider,
I forgot to mention, but for optimal use of your time on those 40 mins treadmill sessions, you could possibly do one weekly tempo session: 10 mins warm up, followed by 20/25 mins at your current half-marathon pace, building up progressively to your target half-marathon pace (1h16/1h17), followed by a 5/10 mins warm down.
Add to that, weekly, one of the intervals session I suggested above (I like to do the Ks rep. on a fortnightly basis, as it gives me a good indication of my current form); one hills reps. session or fartlek; one long run (1H30 mins in preparation for the half), and the remaining 2 sessions easy jogs.
This is essentially very similar to what Donutto suggested, and should be fairly optimal preparation for a 10K/half-m racing schedule given the time constraints that you have... Let us know how you get on..