I'll second Joppa's suggestions. I spent 7 miserable years when I first got to France and married my French husband - mostly immigration and assimilation issues, but with a few health and personal issues thrown into the mix.
First you need to identify just exactly what it is you don't like about where you are. And then you need to take a long, hard, cold look at what you can expect if you return to the US after 3 years away. Nitty gritty stuff like: will your husband come with you? if he does, can he make a living or will you be dependent on your income? what are your job chances back in the States (in the current economy)?
If hubby won't go back with you, are you ready for the legal hassle of separation and divorce? How will this affect the kids?
Other than the kids, I've been through this decision process (over and over during that 7 year period of time) and ultimately I came to the conclusion that I could do something about my situation in France (and in my case it came down to the fact that my French husband would be far more miserable in the US than I was in France). But you have to consider your own situation and take into account everything you will gain vs. everything you'll be giving up to move back (on your own or en famille).
Let me just remind you that, being gone 3 years, you have no credit record, no insurance record (for car or health insurance) and looking for work you'll be seen as having a 3 year hole in your resume, even if you were working in the UK. I've been through this drill - having gone back to the US after only one year away on a job-sponsored transfer where I had the promise of a job on my return - even that didn't go smoothly.
Let us know if we can help in some way with the problems you're having. Just be very careful to be very realistic about what your options are.
Cheers,
Bev