I am a FT working mom of four little ones (6 yrs, 4 yrs, 2 yrs and 1) so I understand. I am out of the house at 7:15 and home at 6:30pm - long long days. My husband works out of town every other week - so solo night-parent a fair bit.
All I can say is it isn't easy.
I have help - a cleaning lady once a week (who cleans, changes beds and does some laundry) and a full time nanny that helps with keeping the kiddos rooms neat & tidy, and a little bit of laundry and will start dinner. So, I have it easier than most.
I did use to have three kiddos in daycare (with only cleaning lady help so I understand). Dinner at night when everyone got home at 6:30 was really really tough.
1) Quality versus quantity - you have to be 100% on when you get home to when they go to bed. Hopefully, you have a bit of a commute home so you can relax a bit 'alone'. I typically read to everyone, even when home alone, in the 2 hours I am home with them. I have quick quick dinners (sometimes prepared, but sometimes from scratch).
2) Meals - in the winter I freeze a fair bit - chicken parmigan (/sp?) in is an awesome frozen meal. We do eat too many nuggets (with fresh veggies on the side) - so not awesome food but still OK. I also do eggs once a week - very quick, but a bit breakfasty.
3)Weekends (days off) - don't overschedule your weekends with activities. I have even given up swim lessons on the weekends - instead I go to public swim with my two older kids (during the little ones nap time). We spend time together having fun.
4) Don't feel guilty - it won't help you at all. I work hard at this every day, especially when my kids run to the nanny when she arrives in the morning. Or when the baby screams when she leaves in the evening. My kiddos are happier and the family unit is 'happier' [money, balance, marriage etc.] because I work.
Sure I have more ... but I try to limit my computing to a minute here or there while everyone is awake!