Could you help me think through the practicalities of leaving?

[girlinabox]

I really need to leave my marriage and feel very clear abou this decision. I can see where I need to get to, and a very lucky to have a good job and will be able o have a resonably comfortable life for my and my children. But getting from here to there, and all the things to consider, is driving me crazy. I just don't have a clear plan, and I know if I don't have a clear plan I'll fail.
I think I need to leave the house with the children before telling him. He's quite controlling, and I don't know how he will react. I thought I could keep them with me, until we have agreed an arrangement for them and got that in writing - but then they need to go to school etc - so he could just turn up at pick up?
I'm scared that if he managed to get them home, and then I wasn't at home, they will feel like I have left them.
And a millon other questions! Please could you help me think this through?

Leaving with the kids without telling him is quite unusual op - I take it he's abusive to the point you are worried about what he will say/do in front of the kids? Women's Aid can help you with making a plan to leave safely and they should be able to advise on issues around school pick ups etc.

What is the housing situation - do you own the house or are you renting? If renting is it LHA - if so they can also help with re-housing in cases of domestic abuse.

Are you working? How old are the children? What is the childcare setup?

Thank you for replying. The first isue you raised is the one I'm struggling with - whether he's abusive or not seems to define the approach I take, and what help is available - but I don't find it easy to make that distinction. His controlling behaviour is the reason I am leaving - however, I don't think he would hurt me or the children. I'm more worried about them being upset by his reaction (he will obviously be upset and possibly angry, just as part of a normal reaction), and him dragging me into conversations and making me doubt myself.
My initial thoughts were to sit down with him and have the conversation while the kids are at school - friends and family have advised against that. I'm still tempted though, as the other way seems very dramatic. I thought perhaps I could tell him, but have an emergency back up plan, in case things get very difficult? Or have someone with me when I tell him?
I rang women's aid I didn't find them very helpful - which I think again comes down to this abusive/not-abusive distinction.
We are privately renting - both names on the agreement, but I pay all rent and bills and he would struggle to. Both children are at school, oldest one just started secondary and I really don't want to cause disruption.
I work full time but with flexibility so don't have any childcare concerns - I think I could tell work what was happening and they would be supportive.

Thinking about it, I could tell him, and have my parents/someone else on stand by to get the kids from school and take them home if necessary.