Depending on my route my commute is either 12 miles or 16 miles, so a little shorter than your 30km but close enough I suppose. I normally take the 12 mile route because I'm always doing too much in the morning and leave too late to take the 16
I commute 3-4 days a week, depending. What I decided to do on the commute was to ride in a bigger gear than I've trained in all season. I rode in the small ring all summer, and now have shifted to the big ring. I also try not to shift out of it if possible. It's a comfortable gear so I'm not killing my knees, but it works my legs more. On my way home, I'll try to hammer more. I don't have a shower at school, so hammering in isn't a good thing. Though Friday I had to because I left really late. This is my current training schedule for the aquabike I'm doing in November, at least for the bike. On the weekend is when I do the swim and bike, though I'm going to try to add at least one morning where I swim, then bike into school.
I have no idea how informative that was, but that's what I'm doing. I'm not an experienced tri person though
"Only the meek get pinched, the bold survive"