Hi Sam,
Georgina Jennings and Steve Hope ride with a mixed group on a saturday morning from Helpston , i understand they go roughly 30 miles and at a good pace , theyre certainly not slow and have no doubt you'll keep with them. It might be worth you contacting George or Steve Hope to find out more.
Also , have you tried contacting Terry Wrights - they might have a group that ride out ?
Hey....Dawn does a spinning class on a Saturday morning at the gym should the weather not be too good - if you havent had a class with her i think you'll find her very good, shes a tough cookie and puts you through it.