Chris, I have a very similar commute although not quite the same hectic life. My 9.5k ride to work takes 20 mins and ride home typically just under 50 mins, all downhill there, all uphill coming home. It never gets easy and it never will, uphills just aren’t that easy, there was a quote somewhere by lance armstrong that basically said anyone that says they flew uphill is talking bollocks.
I’m a bit of a fair weather commuter and cycled for the first time this year a few weeks back, took me an hour to get home, so i obviously lost some fitness by not cycling the last few months. I think your body can only adapt to a certain point, you won’t keep getting better and better and you’ll reach a plateau.
My fastest time home was 44 minutes one day when i was really pissed off, I guess sometimes you just need the motivation to bus your ass. Still annoyed by a friend however that would regularly do it sub 40.