That's a pretty ordinary P&C - very unprofessional. Do you know if there are any representatives from the school like the Principal or teachers that attend meetings? Maybe they don't know how unreceptive they are of you who make the effort, but get shot down. If that's the case, I would approach the Principal about it and tell them that you and others have tried to join in but are made to feel unwelcome etc and that you have great ideas to share but get shot down/ignored. As for the time thing, it may be hard to get that changed as most school committes have times like that to allow for maximum exposure to attract parents who work etc and can't attend earlier in the day. We actually changed our preschool committee meeting time to a later one as we could get more parents that way for the reasons that are stopping you from going - so maybe having it later could be a better option?

But in my experience of clique committees is that you will never get them to change - you just have to wait till they get sick of it and don't stand for re-election at the AGM and then jump in yourself.