If you dont buy (and therefore dont eat) the snack food, think how much money you will save. It needs you to make a decision that everyone in the house will be healthy eating, but perfectly doable to just stop buying all snack food.
I spend a competitively similar amount on food shopping to you, if you multiply up for my big family. There are 2 adults, 2 teenagers and 2 children in our house. I spend roughly £60-80 weekly in the supermarket on everything apart from fresh food. I then spend another £60-£80 ish on fruit, vegetables and salad stuff through the week. But I have roughly double the mouths to feed than you, and do so on around double the budget.
Cooking from scratch really is the cheapest option. I do a lot of "meat and 3 veg" type meals. Chicken, fish fillets, various steaks etc. Even quorn sausages go down well (very low fat and low calorie). With 3 types of non-startchy veg.
Then there's loads of one-pot meals. Bolognese sauce (peppers, onions, tin of tomatoes, mince), savoury mince (onions, mushrooms, peas, grated carrot and stock), healthy BBQ sauce (3 peppers, tin of tomatoes, worstershire sauce and dark soy sauce, blitzed once cooked and add in whatever meat you want). Lamb and lentil stew is another favourite (Lamb, sweet potatoes, carrots, orange lentils, passata).
All of these I've mentioned so far can be cooked in about 30 minutes. Maybe 15 mins extra needed to peel and chop veg before starting, but we are not talking masses of cooking time needed and once they are in/on the oven you can mostly just leave them to cook. So not labour intensive.
I've lost nearly 8 stone since January 2018. My husband has lost 6 stone. Because I decides to stop buying crap food and cook everything from raw ingredients.
Same for lunches - cut out processes crap. Salads are cheap. Or blitz up some chickpeas and make some veggie sticks to drop in it. Or steam a chicken breast and have with veg if you're at home.
For exercise - start walking. Then start thinking about the Couch to 5K program, to teach youself how to run (don't discount as ludicrous, you may surprise yourself).