There are some good tips on marathon training on a recent thread called marathon schedules I think.
Also, what is your reason for wanting to do a marathon right now? If you're happy to do it on minimum training, then you can probably squeeze in enough to get around, although if it's causing difficulties already, it can only get more pressured as you really do need the long runs. On the other hand, will you be frustrated and feel compromised knowing you want to do more, and perhaps creating friction at home? Then maybe it's better to wait until your kids are older or you have more flexibility in your schedule. When my kids were little I just didn't have the ability/energy/time/sleep/focus to take on any more than just looking after them and working. It was a happy time, and goes so quickly.
Everyone's circumstances and goals are different though but marathon training is a huge commitment, and mentally absorbing as well, so you'll need supportive people around you or it's a very lonely journey ahead.
Good luck whatever you decide.