Praise be to Allah.
Settling in a kafir country is not permissible unless certain conditions are met, the most important of which are that the one who does that is sufficiently religiously committed to protect himself against desires; he has sufficient knowledge and insight to protect himself against specious arguments; he is able to practice his religion openly; and he feels safe for himself and his family. For further details on that, please see the answers to questions no. 13363 and 27211.
There is no doubt that taking the children and moving to this country involves many serious dangers to their religious commitment and morals, especially for girls at the adolescent stage. It seems that this is the reason why your husband does not want you to go and join him. It is not appropriate for you to interpret that as meaning that he does not love you and that the bond between you has become weak. You should not think that your husband is happier when he is far away from his wife and children. The Shaytan is keen to exploit such matters in order to spread poison and provoke doubt and suspicion. So you should beware of that.
Weighing up between staying in a country where you feel like a stranger and feel lonely, but you do not have to worry about your children’s upbringing, and moving to a country where there are many dangers to a sound upbringing and there are great possibilities of going astray, is something that requires careful study and examination of all possible circumstances. It may be that no one can do that except both of you. So seek the help of Allah and consult one another about this matter; discuss it from all angles whilst focusing on the pros and cons. Islam came to achieve and perfect what is in people’s best interests, and to ward off and reduce what may corrupt them. We will present a few points to you that could help you to weigh up these matters.
Your daughter may be able to study in an Islamic school in the United Kingdom. This may strengthen the case for you moving to join your husband. Then you would be reunited, you will no longer feel lonely and both of you would be able to attain the rights prescribed in sharee‘ah of shelter, love and stability, and thus your husband will be able to supervise his oldest son, and direct him and ward off a great deal of harm from him.
Similarly, if it is possible for your daughter to follow a course of study through distance learning in the United Kingdom or elsewhere, so that she will be safe from the evil effects of mixing, that will support the idea of your moving.
If your need for your husband is urgent and you fear for yourself if you stay alone, then you should definitely move so as to ward off this problem.
Your choice should not involve your daughter studying in a mixed school, because there is no doubt that mixed schools are haram and organised studies are not obligatory for girls; rather a girl is required to learn what she needs of her religion, and this can be achieved through many means, such as attending classes and seminars, benefitting from Islamic centres, satellite channels, the internet and so on, if there is someone who can support the girl such as a father or mother or husband. Then it is not essential for her to study with the aim of getting a job. The necessity of preserving religious commitment takes precedence over completing education or attaining high positions.
What we are inclined towards in general is to bring the family together in one place, even if that means missing out on some benefits, because the problems that result from the family being scattered are greater than the benefits thereof, as it appears to us.
We ask Allah to help and guide you both.
And Allah knows best.