Elles - The best thing you can do is go with your instincts. YOUR baby, YOU know best. You'll get all sorts of conflicting advice from reading books anyway.
Listen to your baby, and take your cues from how well or not so well things seem to be doing.
Whatever you do, unless there's some bloody good reason why you shouldn't be doing it, carry on doing it if it works. If your baby is happy and contented, then don't let some well meaning relative or ignorant health visitor (yes, even health visitors can give stupid advice) tell you otherwise.
That's about it really for that.
Kater - haha oh the over drinking for the scans. I've done that too a few times. Glad everything went well.
randdom - the tiredness only gets worse in the last tri. Rest whilst you can (easier said than done when your body is feeling uncomfortable, I do realise this.) In many ways though, it does get easier when baby comes along. Well it does if you co-sleep anyway (which is an entirely personal choice). I get more sleep now with a baby than I did when I was pregnant.