I worked full-time with three kids under 5 years old. I was also studying. Not much time to do anything but no budget to go buy fast food.
I cooked in bulk on weekends and froze it in small portions so I could get out a pack of something and accommodate different tastes. I'd cook one-pot meals (I have a store of recipes of you want).
I also would hit the ground running as I got home after work. I'f walk in, grab food out of the fridge and put it in the microwave oven. Then it was back out the door to collect the mail, go start the washing machine. Get the package out of the microwave oven, serve it up for the kids and settle them to eat. Then throw in the next package for me and husband. Meanwhile I would get out the ingredients to cook another meal on the stove, getting it to simmer stage while the washing finished and the kids ate dinner. Once this new meal (for tomorrow night) was simmering slowly it was time to hang out the washing. The kids would be finished dinner by this stage (I always fed the kids first, getting their hunger dealt with made them nicer to know) so I would put them in the bath. husband & I would eat (in turns if necessary, so we could then take turns watching the kids and reading to them). Maybe he or I would get in the bath with the kids, that way we got clean AND watched them at the same time.
Kids settled in bed, husband & I would have a bit of time to ourselves and before bed, we'd turn off the stove and put the casserole in the fridge for the next night. We'd used our time well - the pre-prepared food was ready to be eaten ASAP, but the time we naturally had to take getting dinner eaten, washing done, kids bathed - we used for the cooking time for the slow-cook on the stove.
We couldn't use the crockpot because we were away from home for TOO long, the food would cook to a tasteless pulp if we left it all day. So this method worked for us.
When the kids were really little, I would take (pre-prepared, frozen) home-cooked meals to the childcare centre for them, or at the later centre they had a chef who fed the kids so I could get away with occasional junk food. Or when I travelled on public transport with a baby, I would open a tin of baby food and feed the baby from it, while standing up on a crowded train. I had it down to a fine art. That way the baby was fed by the time we got home. I also breast-fed the baby on the train, and was able to do it very discreetly. The more crowded the train, the less people take notice of one another. Wearing a large poncho, I could feed the baby without anyone even knowing there was a baby under there.
For fast meals when you're tired, last night's casserole either didn't work out or you just don't feel like it tonight - omelette is a great fast standby. And salad.
There were times when I was so extremely tired, I didn't even want to take the time to cook an omelette, so I made an egg flip and drank it down then went to bed.
Fast food - it's not always that fast. At least, the better quality stuff that isn't already sitting there dehydrating, takes time. Sometimes you may as well just forget about ordering the fast food if it means hanging around waiting for it, and instead just go home and cook it yourself. It won't save you any time, but it will save you money.
Marg