Hey @jarkjarks 
I am not able to find your TR account, so I will make a suggestion without having looked at your training history, haha.
If the Saturday Group Ride is non-negotiable, for a low-volume plan, I would recommend changing it to a Masters Plan (2 intervals + 1 Endurance ride) and switching the Endurance ride to a Group Ride.
This way, you don’t have to think about which session to sacrifice on each Phase and the Group Ride workout card will have instructions on how to tackle the ride (if possible).
Ideally, your schedule would look like this:
Monday: OFF
Tuesday: Hard Intervals (TR Workout)
Wednesday: OFF
Thursday: Hard Intervals (TR Workout)
Friday: OFF
Saturday: Endurance Workout swapped to be a Group Ride
Sunday: OFF