If you can manage not to snack that’s already going to make a big difference. If anything, I think that’s the hardest thing!
For breakfast you could just do an easy swap to some whole grain toast - a crumpet may actually have less calories, but won’t keep you full for as long.
Small bowl of porridge or maybe some plain yoghurt with strawberries is I think preferable but might not be your thing.
I would encourage breakfast because for lunch I would cut out the crisps and chocolate bar - if you’re really hungry by lunch time it will be harder to resist them! Ham is pretty lean, I would pair with a good quality bread (whole grain sourdough is pricey but great for your gut health, which in turn is good for weight loss). Avoid any Mayo or too much spread in there. Swap the crisps and chocolate bar for a big pile of carrot and cucumber sticks, and other salad food you might like. Carrot sticks are great because they take ages to chew so again you’ll feel like you’ve eaten a lot. You could also have the apple but if you can hold out, keep it as snack for later if you’re peckish again.
Tea is trickier… how old is your oldest? My LO and I enjoy making our own pizza, you can make a big dough, divide it and store in the freezer to defrost as needed. Then add some tomato purée or tinned tomatoes, healthy toppings (I think broccoli on pizza is great) and a small amount of mozzarella cheese. Keep the portion size small and eat with cucumber on the side or other salad type foods you can manage.
Again, not as quick but if you get some lean mince to make homemade burgers it can make a big difference in calories. Swap chips for veg or salad as a side. Go for whole grain buns instead of white or even cut the bun out completely if you can. Go easy on any condiments. I’d say if you’re trying to lose weight stay away from Mayo. It packs such a big calorie punch for what it is.
Jacket potatoes are so filling, low in fat and high in fibre. Pair with beans or tuna. Just go easy on the cheese.
Pasta gets a bad rep but it is actually a slow release carb and keeps you very full. Stick with tomato based sauces instead of creamy and go very easy on the portion - again have your root veg and salad veg on the side to help fill you up.
Do you like fish? It’s great for just sticking in the oven wrapped in tin foil, and pairing with all the root veg you like.
You didn’t mention drinks - but that’s where a lot of people stock up on calories without realising. So be weary there. Water is best and unsweetened tea or coffee.
That is still a fair amount of food when you’re trying to lose weight - so it won’t be quick, but I think if you’re so busy and have two kids and work to contend with going really low calorie to lose weight fast isn’t going to work well, you need the energy. If you find you’re not losing weight then cut down on portion size again as you may still be eating too much.
Being on your feet all day three days a week is already good too. While it’s still summer, I would say do what you can in terms of activity by getting out and about with the kids as much as possible. If you’re stationary most of the day then you will need to eat quite a bit less, but that can be so hard - I find it easier to keep on the move so I can eat more and stay feeling full.
If possible, a quick home workout after the kids are in bed would be a good way to get some cardio in. But I understand that after a long day that’s easier said than done!