Yes, it is easier when you can say 'He did x' rather than, he was a dickhead/abusive/nasty and have people try to talk you into 'working it out for the childrens sake'/
What do I tell work?
It depends entirely on what they are like, whether you will get support or not.
I'm supposed to be going to away next weekend on a work thing - do I still go??
Do you want to go? If you want to go and your parents don't mind having the kids, then yes, go. But don't get drunk and shag the boss :)
How much of a cock is he going to be about things?
I don't know, I would say it probably depends on how much drink he's had at any given time, much the same way he has been for the last couple of years?!
The biggest concern is financial. I have CC debts (nothing to do with him) but it makes money tight and there's no way I can pay the mortgage and bills here on my own. We have a lot of equity in the house but naff all savings. My preferred option is sell up and I hope he'll let me take the deposit I paid and the money my parents gave us for stamp duty
Talk to a solicitor before you say anything to him!!
The other huge thing is DS starts school on the 8th. What on earth do I do about that if we move??
I don't understand why you are going to your parents, HE should be moving out, not you and the kids. I would tell him he had today to get out then go back tomorrow. Don't worry about DS's school for now, deal with 'what is' it will be a while before things are sorted out with the house etc and you may end up being able to stay in it until the kids are older.
IF DS has to change schools later, then deal with that then :)