Look at the lowcarb boot camp threads here on MN. There is a wealth of resources and guidelines, recipe threads, lots of information on the science behind it and how and why it’s so good for you.
I usually just make enough for my dinner meals that there is plenty left for lunch the next day. Most dinners are very palatable cold for lunch, or you could heat them up if you have a kitchenette.
You need to be eating low carb, high fat or it is much, much harder to stick to (and also doesn’t work very well), and if you broadly follow the boot camp method there actually isn’t any need to count calories at all.
I love lettuce wraps. Works with loads of fillings - Mexican, Thai, coronation chicken, beans and avocado, etc.
I also make salads with lots and lots of veg thrown in, plenty of protein (egg and ham, egg and tuna, chicken, whatever I fancy really) and a good slug of olive oil. Keeps me nicely satiated all day. I keep nuts and seeds and peanut or other nut butter in my drawer so there’s something to eat if I really need a top up.
Once in a while I’ll just bring in a tub of what i term fancy nibbles - (not sure on spelling) or similar cured sausage, cherry tomatoes, cucumber, Serrano ham and cheese roll ups, a boiled egg or two, olives, other antipasti, whatever I can find that broadly goes with the theme.