Firstly, and sorry TR, but some of the fastest endurance riders I know would do similar commuting distances and no added structure. Not sure they can sprint, but they don’t need to!
The other thing I add, I do 1 or 2 16km each way commutes a week on top of 3 TrainerRoad workouts, and quite often I find the double day tough. So I’d agree with start with one structured workout on top (assuming you aren’t lucky enough to have scope for the structure on the commute!).