Second what Soupdragon says - stiff drink needed. I found the amount of paperwork all very overwhelming so put som loud music on whilst I was sorting it. Found it easier to sort into piles and then tackle on pile at a time - almost like eating an elephant
Don't underplay household/personal expenditure. Know how much your life costs and add on more for emergencies. If there is money for the children but in your name, ask to ring fence it so it's not in the settlement. One section at a time. Good luck.
In many cases either people get the list of expenses wrong, or it's not really relevant at all.
There's no point putting down unrealistically high expenditure. Be realistic. Two incomes will have to stretch to 2 households now. Cut your cloth. Don't think you can still afford the same lifestyle. If you put down a list of reasonable income needs that means you have to take all of the ex's income as maintenance then you're living in cloud cuckoo land and the best you'll do is annoy your ex - most likely annoy the judge too.
The times when it's less relevant are when both parties have a similar level of income and it's clearly a clean break case.
In your situation you can do 2 schedules. A is what you're spending now. B is what you can't afford, but what you'd like to be able to afford and think you should get the kind of order that enables you to afford it.
I once acted for a man whose wife, on income support, put in her list the need to spend £56 a month on taking 2 dogs to the doggie hairdresser. Stunning.