I wonder if you are doing the job I used to do?it sounds so similar, so I was faced with a similar dilemma (all except the house move). Often I could be at meetings 100+ miles away, so no chance of getting baby from nursery?and heaven forbid the a traffic jam!
The way I see it is you have two choices, 1. find a plan to make your job work and submit it to your boss and ultimately to your other half letting him the part he needs to play. 2 Do the maths, see if you can quit or get a lower paid job (or even similarly paid job) locally and enjoy the work life balance.
If you want to keep your jobs could you chose a nursery that was very near to your place of work (there are draw backs to that, but a lot of women I know do that and it works for them), would you then be able to be in the office for your contractual hours?
Also?.some points about your job?.you say that you have ?sounded your boss out informally? and that ?he has agreed that he thinks that he thinks it would be impossible?, however, in my experience, I think he would say that on an informal basis as he is paid to get the best (i.e most) out of his team and most bosses, especially male have totally bought into the whole ?long hours is the only way to succeed idea?. This sounds sexist, but the most productive and organised people and ruthless time managers I have ever worked with have women! One of whom was the mentor I was assigned when I was given a fairly hefty promotion, she had 3 kids, so had to leave on the dot at 5pm every day. She achieved in her hour 7 day what a lot of her peers were spending 10 hours doing and she taught me to do the same, very empowering. So I don't always buy the hours thing every single time, if you see places where you can make cuts, or delegate, then see if it could work. That said in this economic environment I think you may need to make provision to do a certain amount of work from home. Also note that it impossible to do a career job working multiple locations without a huge amount of support from your partner.
On the flip side?..if you choose to quite, have you done the maths to see if you can live without the money?if you haven?t already, do a budget and show it to your other half (properly, go through it with him when there is time) and see what he (and you think). Also, if there is a massive deficit it may help him realise that he needs to help out with the child care.
I ended up jumping to take voluntary redundancy, which was a mixed blessing. It?s been blooming tough and financially it?s been/is dire. That said I?m just not sure how life would have been as I would have done a nursery drop at 8, pick up at 6, TV dinner in oven, baby in bed, back in office at 8, out at 10, bed at 10.30. So although things are a bit stressful right now, it?s possible that they are not s stressful as they could have been.
I have also used ACAS is the past, (you can google them) they are free and will tell you your rights from the point of view of the law rather that the point of view of your company.
Ah well....good luck and follow your heart!