I technically work 8.30-5 full time, but a couple of days a week I choose to stay a bit longer, but I'm heading towards a more senior position so I'm choosing to put in some extra hours while I learn what I need to do.
DD is still 3.9, so she's in nursery 8-6 two days a week and with family the other 2.5 days (DH works a short day once a week). It affords us a little extra flexibility and DH is very supportive in picking up the slack after work getting her home and in bed - she falls asleep on the drive home on 'family' days as they're further away than nursery.
My employer is very understanding and can be flexible if I need to come in late or leave early - they know that I can make up the time if necessary so it's not all give on their side.
I don't know about legal environments, so couldn't comment on that. Between my job offer and acceptance I did make sure they knew I had a small child so they wouldn't have a nasty shock if I suddenly had to be late one day. It hasn't happened very often, and in fact the times I've had to request some flexibility have been non-child related emergencies (heating disaster and a couple of car related catastrophes).
Working long hours full time means you have to be really organised during the week, but I waste much less of my weekend than I used to. We do quality, rather than quantity as a pp mentioned.
Good luck, whatever you decide.