You did very well! I was pushing it reasonably hard in the front for most of it.
I agree that the route wasn't the best, but I think it has historical significance for the club. I prefer Wednesday "North London Hills" rides. Obviously those are a bit more testing, but they are definitely good at building up strength/fitness generally.
We probably did about 53km from the park and back. Here is a link to my strava route (which includes my ride to the park and back): http://www.strava.com/activities/170436156
I definitely recommend getting yourself a strava account so that you can start tracking your cycling progress.