You will find that you get "pulled along" in a group so your speed will be lifted to some degree on what you normally ride.
If you are comfortable doing the overall distance, then get stuck in. Have a chat with the club secretary or other official, explain what you are currently riding and discuss with them whether it would be suitable to come along.
They'll either welcome you with open arms or point you in the direction of something more appropriate. Most clubs allow everyone a few trial rides before encouraging membership.