talk to the guys and gals at the local LBS and see if they have any weekly rides for beginners, most do. I would also contact the leader of the women on wheels ride and explain where you are at speed wise and endurance wise and see if the ride is suitable. Most women's groups are fairly flexible, a lot more so than mens or men lead mixed groups, in my experience.
Learn to enjoy riding single. It is an ideal opportunity to build up steady hour speeds, challenge yourself to intervals and push your speed without having to apologize for slowing down, stopping to take a drink, breath etc.
I tend to organize my rides so that one is a long hours easy pace, the next is short, sharp and hard with lots of 1 minute sprints and longer sessions of 5-15minutes of maxing out speed. The third is for long mileage in a moderately brisk pace and anything after that is just easy spinning.
I do like riding in a group but there aren't many opportunities so I have learned to enjoy my solo rides.
Good luck and welcome to the adventure.
marni
marni
Katy, Texas
Trek Madone 6.5- "Red"
Trek Pilot 5.2- " Bebe"
"easily outrun by a chihuahua."