The schedule looks excellent.
I'm not a fan of the term slow pace, it's basically just part of the easy zone. I don't see any point in distinguishing between the two. They should both be done on how you feel on the day.
A good mix of paces, and peaking at about 60m/week. The steady and brisk (threshold) runs are key. I think with a bit of luck you will smash the 3hr mark.
Good luck, I will monitor your progress with much interest.
ps. It's good to see a lady tackle this, it must be the equivalent of 2:45maybe for a man.