I am expecting DC2, DC1 is 10. I earn 3x what my DP does. I am a midwife, earning 34k FT and he works in a supermarket earning 11k varying hours some weeks FT some a bit less.
For us the answer was easy. I work FT, he drops to his basic hours (19.5) and we get childcare for those days. He will then do the odd bit of overtime around my shifts.
Our childcare costs should only come to around £120 a month. We will be using a childminder for 1.5 days a week, and hopefully family for the other day if I am on a shift (its a saturday).
I don't have the liberty of set shifts, or changing my hours, or anything remotely flexible. I work what I get told to. Therefore it makes much more sense for DP to be the one to work less. If he worked FT his take home pay would be the same after paying for the FT childcare, so why not just work less for more rewards (more time with children!) If he wants to do FT he can, the only stipulation is he needs work on set days, then he can do or work wherever he likes. Or he has to earn more than me (and that isn't going to happen!) If he was to work shifts it would be an absolute nightmare. It's just the way it is. And we are happy with our arrangement.
By the way, it would be pointless for me to ever drop my hours. I would still have to pay for the same amount of childcare, and just earn less. When you don't work set days, it all becomes a bit of a nightmare. You might pay for 3 days, but not work those 3, and be in a completely different 3 days... then have to find the extra 3 days childcare.
Every family has their own way of managing things. What we do, works for us. Its probably quite unconventional really. My mum brought me up to be independent financially and to never rely on a man for money, so I am quite glad I earn more to be honest. It means I will never worry about being on my own with children, or if DP lost his job. We'd still get by. I admit to sometimes wishing I could work less, but really, I'd be quite bored!
I also think some people are paying crazy prices for childcare btw. If we had a FT place with a childminder, it would be around £120p/w. Hourly rates start from £2.75. This hasn't changed much from what I was paying for DC1 10 years ago - it was £2.50 p/h back then. That is in the NW.