Monday = walk the bike. just tool around
Tuesday = tempo ride. ride at a comfortable steady pace
Wednesday = steady tempo ride again.
Thursday = intervals. After warm up, go as hard as you can for as long as you can. recover, repeat.
Friday = walk the bike
Saturday&Sunday = ride with the group and do whatever it takes to stay with the group (can be termed inverval/hard workout)

This is the optimum range. If want a day off, the n take one.
If you don't feel like riding interval or hard one day..... then don't.
You are not a motor for your bike. Enjoy yourself.

You are at around 100 miles per week. You can improve greatly with that kind of milage.
You add a longer 40+ group ride on a weekend and you've got yourself a 150 mile week.

Remember to go slow on your slow days and fast/hard on your fast/hard days.

Pay close attention to your resting HR. Each day, after the alarm goes off and you raise your head up off the pillow, take your resting pulse.
Mine is 59 during the season. If it rises by more than 6 or 7 beats, then ease back on your milage.

enjoy.