Sitting down to dinner is an important part of family life. It's a time to connect with everyone and share news about your day. Now with kids that are 3 and 5 it probably doesn't seem important, but it will be when school starts, so you need to set a regular dinner time and stick to it. You also need to limit the snacking. I stopped buying so much snack food and it's amazing how my kids will hold out for dinner when there's nothing "good" to eat in the house.
I had a similar situation when I worked because hubby would get home first a few days a week. We sat down on Sunday and planned a menu and then knew what to do. It's ok if your hubby makes frozen pizza and has some fruit on his nights. The crockpot is good too or even some sandwiches. He doesn't have to be a gourmet chef, but you need some help.
I agree with the other mom on the eating on the go. You need to take a look at what's causing this and slow down. It's great to have lots of activities, but everyone can get stressed out by dashing to and from and it can get tricky to provide healthy meals.