Pom
Firstly -he refuses to take them to parties? What a twat.
Secondly - if he chooses not to have them that weekend because he'll be too hungover, confirm that by email with him (diplomatically phrased of course)
Thirdly, if he can't make his weekend because of something like that, I'd write off the weekend and not rearrange because you've already made plans for the other weekends you have them (even if those plans don't exist) It's unreasonable of him to expect you to cancel plans because he's planning on getting pissed. So you can document he's spending less than one weekend a fortnight with them, and his maintenance payments will be increased accordingly, if those haven't already been finalised.
The half hour late thing - well these things do happen, especially with young kids involved, but no apology is a bit off.
Hrrm - I've lived with single attractive housemates before and there just wasn't anything happening between us - we were friends, that's all. No spark = no involvement. (I may have possibly slept with several of her friends though) -
The passion about clubbing is a bit strange though, if you're not into them. Very different lifestyles if he describes himself as 'passionate' about it.