It's a good thing that you are working this out or trying to resolve before the move because you are very likely going to be confronting this issue if you do move. You DH is not being fair and in all honesty, I would make sure that you get this out on the table and find a resolve that you both can live with before you move! Boundaries need to be set but the truth is, they need to be set whether these people live across the continent or just two streets over. You have an opportunity to live in an area that you are interested in - and no, they (the inlaws) should not deter you from this. However, they also shouldn't be allowed to treat you in the manner that they are. You need to set the boundaries and make sure your DH knows that you will be doing this if he is unable to. However, standing up to them will come at a price. And, if you move across the world and in an area where you feel unable to stand your ground, they will have the upper hand and I'll bet that your DH knows this. As you say, they demand this and that from you when they come for a visit. Why do you allow it? Why do you not move your computer to a private area when they are visiting so that she can't stand over your shoulder? Also, why don't you slip out of the house when she isn't watching to do what you need to do alone or, just tell her that this is something you need to do alone. Or, let your DH take her somewhere so you can have the time you need when they visit?
And, if you move, why do they get to come to your home and stay when clearly it will be very small to house extra people? I guess what you need to do is come up with plan B's that you can live with. For instance, allow them to visit but agree on a certain amount of visits per year and a maxiumum amount of time per visit - and ask that they stay in a hotel close by. Even consider the option of paying for it. Set boundaries that you can live with and don't be afraid to stand up to your DH now - I would put this all in writing and get husband to agree to it by signing that this is acceptable to him as well.
If he won't then that is a tale tell sign and I personally wouldn't even consider a move in that situation. Dh's need to stick up for you and your children and if they can't even commit to that now, then it would be a mistake in my opinion for you to move across the country just to endure more and be isolated in the process!