Glad that she has calmed down. It is good that you are playing a long game and to not close down the conversation because of such a dramatic reaction.
We moved from Sydney to UK a few years ago. Our daughter was 10 and really was excited to come, but after being here a while she developed quite a bit of anxiety about not quite fitting in culturally. She still doesn't have many close friends, but she did not in Australia either and we keep reminding her of that. The 'being exotic' aspect was not a plus for her in her eyes in year 6, it made her stand out. However, in year 9, she is using it for all she is worth and gets a huge laugh out of it now.
We have been back a couple of times and each time she is surprisingly happy to come back to the UK. She still says she misses Australia and will 'never call the UK home!' even though she admits that she has had some incredible opportunities here already that she would never have dreamed of and now treasures.
We have had to work really hard with her on her resilience and remind her to focus on the positive aspects of living here. We certainly don't invalidate her more negative feelings about it at all. It has been so hard sometimes that I felt it might not have been worth it despite that we love it here.
I am happy to say though, it is much easier now. Although she still says she wants to go back for uni - and we are quite ok with that. While she may not yet, it makes her feel good knowing she has options.
Instagram allows her to keep in touch with her friends (and yes, I am very strict about how she uses it and she only has been allowed to use it this year). Even better, she realises that her life is not so bad here
at all because she sees what they are doing and doesn't ever feel a twinge that she wants to be doing the same.
This has been long winded, but I am telling you this so that you know that there is no cut and dried answers despite all the suggestions that this is a disaster of a move on this thread. And we know from our own experience, it took us four years of living in London the first time around (early 2000s) before we felt like we wanted to stay. So, we expected that it would take that amount of time with her too and I think that it will.
I think that you know your situation best. It is definitely doable. That initial shock may very well give way to a sense of adventure soon.
If you need to get some outside help for your daughter to learn that resilience, do get it. In your case, if your DH has no opportunities here due to being in an narrow industry or has very little prospects here, it really is a decision about keeping your family together or not isn't it?
And keep in mind.... that if he got a new job back here in the UK, it might very well mean he is still working away from you Monday to Friday.
Again, there is no cut and dried answers, just what is right for your family.