That makes it sound like you need to be cat 3 to join a team. Around here, I don't see many cat 4's who are unattached, and even most cat 5s are wearing team kit. Joining a local club may be a good move, if they have a racing division (which counts as a team); that's the lowest hurdle to joining a team (at our local club, pretty much you say you'd like to be on the team and you're on) - but it's also a bit anonymous, less of a real team feel, from what I can tell: you're wearing the same kit, but you don't necessarily race/train together. I've not joined our local club because their events are so overwhelmingly aimed at recreational riders - I was lucky to have a few friends on a local team that could use a couple new members.