Lars,
Did this for three years while assigned to a Navy ship in San Diego. This is very hard; harder than you now think.
Here's what I would suggest:
Telephone - Buy a good cell phone plan... I would suggest one with lots of evening and weekend minutes. It is cheaper than a land line at both your home and "apartment."
Food - plan your menu for the week, shop at home, and bring "your" food for the week from home. Double shopping will kill your budget. Also plan to eat "out" (read-fast food) at least 3 times a week because you will want to spend time with classmates or will be too tired to go home and eat.
Commuting - leave home on Sunday evening and go home after your last class of the week (don't wait until the next day). You will die a thousand deaths if you try to drive all the way to school on a Monday morning. If you delay returning home to get a good night's sleep, you'll be leaving for home later and later the next day, cutting into family time. Better to "crash" at home that night.
Laundry - do it at home on the weekend. All other "errands" that take time away from family should be done during the week.
Studying - Study all week. If you have homework over the weekend, do it after the kids go to bed, even if you're up late doing it.
Family - Plan one "thing" for the family to do each weekend... even if it is just going for a ride in the country or shopping at an open air market.
Spouse - during semester breaks, make time for the two of you for a day or two. Get away from the kids and reconnect.
Kids - DON'T bring home "gifts" or try to compensate for not being there. It accentuates your absence. You want this to become "the routine" and natural for the kids.
Household - You have to let your spouse have more control of the household decisions than you'd like. This will be a big area of conflict. You just have to accept that they are making those decisions, often without you, and you'll have to be supportive of their decision. If not, you'll be paving the path to divorce.
Finally, at some point in the semester, have your family "visit" you at school and spend the night at your "apartment" (if possible). Let your kids know where you are at night.
This is very tough. Good luck.
Chief