We alternate and purchase accordingly. I make a weekly menu, once a week. Go to the store twice a week (Saturday for nearly everything, Wednesday for more produce and milk---don't want to buy too much milk and have no room in the fridge at first, and don't want to buy ALL the produce and some go bad mid-week. Whatever meat is on sale at the deli (chicken, turkey, roast beef, ham, etc): I buy it by the slice instead of the pound. On the weekly menu, I've planned what we'll be eating (basically, it's not set in stone but it's my guideline) and I'll buy enough lunchmeat to cover a lunchmeat sandwich 2 days/week. 1 day a week we'll have cucumber and feta sandwiches, another day peanut butter and jelly/jam/honey/whatever preserves we've got on hand (we get fig and blackberry that my mom makes a couple times a year). Another day can be purchased at school or work for something different or hot, or could be a lunch in a thermos (leftover soup, gumbo, jambalaya, pastalaya, sausage & peppers wrapped in flat bread (heated, then wrapped in foil), tuna casserole, pasta salad, etc). At home on weekends they eat hot lunches. An entree and a serving of fruit or veggie sticks with a little container or hummus or dip they help me make is all they need for lunch at this age, it's not like they eat a ton. OR as a treat sometimes, I'll surprise them with a little container of jello or pudding, which is fine, and they end up eating the rest of their sandwich when they get home (they get full, or run out of time, when there's too much in the lunchbox). I did get compliments a couple times last year from my son's kindergarten teacher on packing great lunches, a nice variety (yet easy to plan), and on the fact that my son actually eats ALL of it. I think we should feed our kids "normal" food, there's no such thing as "kid" food in our menu.
For fruits: you can buy a container of fruit that your family will eat in a few days, then mid-week purchase some more like I do, or you can clean them, slice them up, and put powdered sugar on them to help them keep a little longer. Some dried fruits are great options if she'll eat them; we love raisins, dried cranberries, banana chips, trail mix type fruits. Or some things are great frozen too: I like frozen grapes when they're still slushy inside better than just normal temp!
But when it all comes down to it, you'll figure it out as you go. I like what one mom already told you: lunch doesn't have to be "perfect" and you don't have to stress it so much, you're in more control of breakfast, dinner, and after school snacks so focus on those. 2 out of 3 of my guys are great eaters (the youngest is coming along and getting better), so I have a lot of freedom in packing their lunches. If your child is picky, choose your battle, and make the lunch that you're not there to "enforce" eating rules easy on both of you.