All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The decisions of an English court are not valid for Muslims since they do not act according to the Sharee'ah. Your wife was supposed to refer to an Islamic court in a Muslim country; if it is not possible, she should then go to a Muslim scholar, which is very possible through an Islamic Center.
As for taking care of male children, as long as they are older than seven years as you mentioned in your question, they are allowed to choose the parent with whom they wish to live. If they choose their mother; she will take care of them; if they choose their father, he will be responsible for them.
As for the daughter, as long as she is older than seven years, the father is more worthy to take care of her. This is the opinion of Imam Ahmad, since she needs to be protected and this job can be done more perfectly by the father than the mother. Also, she has reached the age of marriage and a girl is married through her father who is her Wali (guardian) and who is more able to seek a suitable person or find out the suitability of a person who proposes to marry her. For the above reasons, a daughter is not allowed to be with her mother if she chooses her, contrarily to the case of male children.
Allah knows best.