From the experience of a number of my friends and family it appears that working in the law is pretty much incompatible with having a young family unless you are prepared to sacrifice the majority of your family time.
My brother qualified as a barrister and now works in legal compliance for a city bank. He earns very good money but is out of the house in the week for all of his children's waking hours. (He is completely free weekends though). His wife, my SIL, was a successful solicitor, about to be made partner, and she gave it up completely to be a SAHM as she felt her priorities had changed after having children.
Another friend, qualified solicitor, doing very well in a small firm, had to leave her job when her husband left her as she couldn't manage the childcare. She now works part-time in the legal department of her local council and is much happier.
Another friend, qualified solicitor, never went back to work after her first child. She now has 3 children under 6 and is a SAHM.
If I were you I think I'd be looking for a smaller firm to be doing a less prestigious training contract, with a view to qualifying, then using your qualified status to get a job, not in a legal practice, but doing something law-related. This, from my friends' experiences can lead to a better work/life balance.
Those who have said that it is more standard for people to attempt to qualify pre-children are correct, and I can imagine how tough it is for you trying to juggle everything. Good luck with whatever you decide.