You could let him have Wed-Sat, and then you have Sat-Wed each week, with handover at teatime on Saturday so the weekend is shared. That's a nice easy pattern for arranging working hours around.
If he's having them nearly 50% of the time I think there's two ways of looking at the finances - Either you split the care, and you also split the costs. So every time there's a school trip, new clothes needed, etc you split it. Means you need to agree on what to spend the money on.
Or, he pays you maintenance, and then you cover all the costs other than food, etc when they're with him. What he pays you you can decide between you, though CSA would work it out at 20% of net income, and then reduce it by 3/7 for having them 3 nights a week, so it would end up around £300 a month I guess - you can work it out more precisely on their website, though that's assuming his pay is all declared. Anything that's cash in hand and not on his tax return with be invisible to the CSA, so if you're hoping for more than they'd award you you'd be relying on his goodwill.
Our two DDs are nearly 9 and 5. Plan to separate and divorce after Christmas due to feeling unloved and neglected in my marriage. I no longer love my DH and although its causing me lots of guilt, it's what I want I plan to move out with the kids and buy a smaller home once DH has bought me out of the family home. He's reluctant to pay any maintenance (self employed with £2900 take home pay per month!!) lol! We both want a fair amount of time with the kids and in a pattern thats bet for them. I can't pick kids up on Friday from school due to working late.. What kind of pattern could work? And how much maintenance is appropriate for him to pay?? I'm thinking that in every fortnight, kids sleep at his 6 nights and at mine 8 nights. Thanks