hookyhookyJust so you know (I don't know if you've played TF2 competitively or had previous knowledge), competitive TF2 is completely different from QWTF, and even TFC. We currently play in a 6v6 format with 4 main classes: 1 medic, 1 demo, 2 scouts, 1 roaming soldier, and 1 pocket soldier. Any other class is only occasionally used (often in the case of sniper) by the scouts and roamer.
If you are new to comp TF2, I'd recommend trying out newbie mixes, which usually happen on Friday nights. Then you could try IRC pugs.
Ah I see. Well I have not played that 6v6 comp competitively but been in plenty of organized matches with other types. I'll check out the newbie mixes group.