D.T.
B. - First I feel your pain I work full time and I know what it is like to come up and have nothing done very frustrating. But he is also an example for your two children I would not have the arguement or ask him to try to understand you I don't think he can. Also I think your 4yo doesn't know to ask dad for lunch or to do stuff that isn't what your 4yo thinks is the role that dad plays. I would sit down both your 4yo and your husband and explain that summer is here and there are some things we need to do daily and you are trying to teach the kids responsiblity. You will have a list for them each morn. First your 4 year old can help and his jobs should include matching socks or putting them in the correct drawer, it might be cleaning the sink in the bathroom, it might be putting the cups in the dishwasher it might be putting his toys away, what can he do for the 2yo put those toys away whatever your 4yo is capable of and if he can't read draw pictures and explain in detail what you need done. I will tell you I don't do jobs I could get done in a second so I can leave them for my kids your little one should have two or three things on that list. Your husbands should have whatever but probably not more than 5 in the beginning. Very clearly the goal is to have the list done by the time I get home. Make it very short for the first week and then you can add things to the list. If it is not done I turn off the TV and everyone comes inside until you get it done - not so fun :) The other thing is when your husband does his stuff and your 4yo does his you celebrate like there is no tomorrow wow great job mommy really apprecaiates the help blah-blah-blah. Even if only your 4yo does the list still celebrate your husband will see this and how happy you are. There needs to be a sense of accomplishment for both of them. Also your husband won't let your 4yo be unsafe so if he is doing these things he might actually help.
Here is my suggestion on the food thing which I have lived. I keep a snack basket in my pantry and in it are healthy snacks. Each child can have max 2 healthy snacks a day and they can help themself. You can make lunch and have it on the shelf in the frig ready for your 4yo to get it all by himself. It might only be cheese and crackers but it is there and ready. When you call home during the day you can ask your 4yo did you have the snack from the basket or did you have lunch did you do your job? And if the answer is no he can go get it done. Is there a lot less work for you no not at the beginning but in the end there will be and by the time you get home some things will be done and you will be less stressed - you are making a new routine :) Good luck.