Hi!
I'm also a grad student (systematic theology) and a new pipe student. 45 minutes a week won't cut it, but you can take your PC to school with you and practice between classes...even if it takes going out to practice in your car!
If you look at your schedule, you most likely can find some little slots of time throughout the day where you can get some practice in...four 15 minute sessions a day gives you an hour (and it can be a great stress relief type of break from study)!
Good luck!