I grew up in Dallas and lived for a number of years in Austin. Austin, to my mind, is a great place to be, and not just because it's a liberal oasis in a staunchly conservative, Republican state. Mostly, it's because there's so much going on there all the time. Cool stuff. Great music, fun events, (mostly) laid back people. The summer isn't as humid as in Houston and the winter isn't as harsh as in Dallas. So, if your husband can at all swing it, try to get a job in Austin.
Now, saying all that, I think it's possible to carve out your own little niche wherever you are. If you go out looking for activities and places that interest you, you'll find kindred spirits. The worst thing you can do is go with a pre-conceived idea of a place. I made that mistake when I moved to Florida (Tampa). I thought it would be a hip little beach community like I'd experienced living in San Diego. Boy was I wrong, and I hated it.
Personally I think Texas is great and I'm proud to be a native. There are things I'm not proud of, like the good ol' boy culture and the freaky religious folks, but you can avoid them pretty easily by finding people that you identify with. Dallas is a big place, you'll definitely find them! It has a very diverse and multi-cultural population. It's too big for me, which is my main objection to it now, but I honestly don't think you'll have trouble settling in. If you've been able to settle in the UK, you obviously are open to change and new surroundings. If you had said you were moving to some small backwater town I'd be more concerned, but I'd wager Dallas is pretty much like any other major city - with nice people, mean people, cool people, weird people, religious nuts, live and let live types, and just plain crazies.
Just my two cents, for what they're worth. Hope it helps.
Lee
PS - Austin is only a three-hour drive from Dallas so even if your DH doesn't get a job there, you can visit!