No haven't found a class yet. What nationality are you. I think you should do advance you will pick up much more that way.
You prob won't find a similar age group unless it's at uni or something because from what I gather, Polish classes aren't of that great a demand. But I have studied with adults and it's been great fun and I haven't felt at a disadvantage because of my age ever. So if you're really keen you should just give them a go.
I'm Eurasian; half English half Filippina. Why? You're Polish I presume?
I think I would pick up more in Advanced, but the thing is a lot of the people who are now in Advanced also did more than one semester of post-beginners, to get to that level, so I might just do what they did for now.
I emailed the schools at North Ryde and Ashfield a couple of days back but haven't got any replies. My Linguistics lecturer at Uni is Russian though and she has helped me with some of my Polish issues so I will talk to her and see if she knows anyone / what I should do. But until next semester I think I will probably stick with post-beginners, see how I go, if it's too easy request for alternative work and/or work on my own out of books in my own time?