The
WTCA site has group ride schedules and contact information posted. Scheduled rides are just about every day of the week.
I'm sure if you contact a member or any of the LBS's you can hook up with someone in the area for one of the scheduled rides or even an unscheduled ride/event.
I know of four bike shops in Lubbock:
DFC
Broadway Bikes
Velocity Bike Shop
South Plains Cycles