Ride the linear track to the coast as a beginner, i used it all the time when starting.
I still use it to ride home from Nth Adelaide on weekday commutes.
Most of my weekend riding occurs on Sunday late morning early arvo(50/75 k's) if and when a window opens.Work and kids sport means it's a little sporadic though.
I personally prefer to ride solo,as I tend to ride at my own pace and find that most the casual friendly groups rides I've tried are a little on the slow side.My average is not high, but 30 k's average seems to put me in a no mans land, where I'm faster than casual and lower than serious riders.
Plenty of friendly people here
http://www.adelaidecyclists.com/ too, including some from out our way.
Are you on a drop bar roadie, flat bar/hybrid or something else?