Tavish would have arrived a few moments late, he was surprisingly struck by Silas' appearance and would have spent a great deal of time with her because of that. Over all he was jovial, if a little shy of loud noises (a little bit of a lingering headache) and wouldn't have made any actually mention of his drunken shenanigans on the journals the night before. In fact, the only way it would have been evident he was even aware of them would have been a general avoidance of Millicent.
His manner would have implied a jovial, happy, social man who very much likes attention- nothing all that unusual for him. He would have made sure to talk to Minister Malfoy, though again- no mention of his stunt- and would have made conversation with anyone around. The major change in his demeanor would have been a slightly decreased flirtation with other women.
Of course, Tavish was dressed in tailored robes, black and white, that were custom designed and fit him perfectly. His way of wearing perfect clothes like these typically leans toward relaxed, as if he puts no effort into looking good (an illusion, I assure you.)
His to-see list would include Alex, Blaise, Adrian, and Roger for sure. I'd love to thread any of it!