I'm doing something similar to you, loosely based on Galloway. I do 2 short runs during the week which are 30 minutes/2.5 miles. One long run on the weekend. Yesterday was 7 miles. I add .5 miles every week. I try not to do intervals during my short runs but always do them on my long runs. I'm doing 2:1's for at least the first half of the long run. As I get closer to the end I let myself run longer if it feels right.