+1 to DavidL's post. Remember that it's not a race and you're halfway home.
Biggest potential hazard is other cyclists that haven't been in a bunch all that often. If that's you, take a little time to learn a few generic signals so you know what's coming up and can signal others behind you.
Inaminit's definitions are pretty accurate:
viewtopic.php?f=12&t=3915&start=0"Although they can vary slightly between groups, some of the common hand signals are :
Arm outstretched at about shoulder height = turning.
hand pointing out to side at waist height = rider moving over or preparing to pass someone on that side.
Hand waving low to side or pointing to road = an obstacle to be aware of on that side of the rider but not directly in the current riding line.
Left Hand waving behind riders back = merge over to the right to avoid obstacle in current riding line. Can also mean go single file.
Right hand waving behind riders back = merge over to the left to avoid obstacle in current riding line. Can also mean go single file.
Hand behind seat with palm facing out = slowing or stopping.
And one I saw for the first time today....
Hand straight up in the air with a closed fist = slowing or stopping.
Whenever I join a group for the first time I try to sit at the back and get a feel for not only the hand signals they use but their voice calls too...remember if you're confused by their signals and calls, then chances are they'll be confused by yours too. Best to play it safe until you are all speaking the same lingo."
Take it easy and you'll be fine.
ta !
and I think will drive me nuts the whole way
I nearly cleaned up a few at a set of lights I almost missed. Learned the hand signals quickly and paid attention. I didn't like my bike being rather roughly stacked on the ferry though. 
