My son believes I don't do anything for him - I do everything I possibly can & yes there are things I forget to do (as I'm only human). He is sly & causes arguements between his father & myself that I am being mean. He tells me I do nothing & that I'm lazy, he lies on the couch & demands I get him this & that for him (which I don't of course). He never speaks to me like this when his father is around. I'm at the point atm that I'm going to make him do his own washing, pack his own lunch box, etc. (do all my daily jobs) because I think he might learn to appreciate the things I do for him to make his life easier, yet I feel bad, as he is only a child still. Am I dealing with like a parent should or any other advice would be helpful?
You have provided a lot of useful information in your question, so I hope I am able to help.
First, he "believes I don't do anything for him" -- I doubt this is what he believes. It is what he says, absolutely, but let's look at what he is saying. He is calling you lazy (and I presume other things). Children do not make such statements unless they have seen that behavior elsewhere and then they mimic it. Now is the time to end it. Yes, in some cultures women are still considered as those who serve the males, but there are various levels of "serving" -- we can provide various services or we can actually be servants who are beholden to those we serve. One is demeaning, while the other is not.
Second, that he "causes arguments" and does these things only when your husband is not around is actually not something I suggest as directly involving your son. Your husband needs to know and act upon his son's behavior. When a man is raising another future man, that man must train him to be a strong, quality man. You will not be able to equally substitute for your husband's influence, nor should you have to. Speak with your husband and decide on how things will be handled. A dual front in working with your son to be a great person will mean all the difference. And in those cases where you and your husband have differing views, they should be settled outside the view of your son at this point because your son is gaining a benefit from seeing the differing views.
Chores as a penalty will not serve the purpose intended. However, at 12yo as the commenter added, chores are a part of most people's lives. Want to watch TV? When your chores are done. End of story. -- etc, etc.
Regardless of your gender, one must be taught proper respect for the other gender. And completely independent of gender, one must be taught proper respect for all others.
My biggest concern is that your question appears to be asking what you can do without the father's input. Raising a child, though, where you are fortunate enough to be a 2-parent family must include both parents to be successful.
Notify your husband. He should not solve the problem for you. But he must know what's going on because you need to act on it. If you fail to notify him, it will come as a surprise to him and you may lose.
Men will naturally try to provide an immediate solution. Tell him that since this behaviour does not happen in front of him, he can't really react or discipline his son for things he's heard from you.
So far for your husband.
For you, I single out one line from your question:
There is your problem. Even this is true (which, at 12 years, is questionable), he certainly does not want to be a child. And he certainly does not want to be treated like one.
Letting him do his own chores is an understandable reaction, but it is also power-play. You are making him do chores, because you are the Boss and he is the Child.
It would be more productive to approach him differently. Approach him like an adult, with rights and responsibilities.
He is 12. He is starting to grow up - a lot. And your way of interacting with him must grow up as well.