You will love a Woman Tours trip. I have done two: the Outer Banks of NC and the Natchez Trace in Mississippi. I would love to do another one. Maybe the next big birthday!
On my first trip, there was a wide range of ages with some younger women in their early thirties. On my second trip, I was probably the youngest -in my early 40's. It doesn't matter. You will have a great time regardless of the ages. Women who bike have something in common, and women who will go on a biking tour usually are interesting personalities! There have been single women travelers on both trips. Their literature says that the majority of their riders come alone.
I can't recommend it highly enough. The food is wonderful (don't count on losiing any weight), and they stay in really nice places.
Grits
2010 Trek 5.2 Madone WSD, SI Diva Gel Flow
2002 Terry Classic, Terry Liberator