i am concerned about your well-being at this time. one's emotional body affects the physical body. you've been through a lot already.
putting the money issue aside for a moment (as that is solvable), it seems possible that birthing here in the uk rids you perhaps of the custody issue. it would be good to know the facts, perhaps something to research further.
perhaps that is not a huge issue to you at this moment, but considering that alcoholism is a progressive disease, it could very well spare you much hassle and being tied to your alcoholic in the future.
you could always simply say you need your mum right now, which is actually the truth! your trip could be proposed for that reason, to both your man and the children.
as for his children, your reality is that you have no rights to them and will not be able to spare them your alcoholic's madness.
i don't know. i need to reflect on this further. right now, i see it as a ship that's sinking...do you spare 2 or do all 4 go down with the alcoholic?
if you are the praying sort, it might be a good time to request HP's guidance.
please, forgive me if i overstep my boundary...your first post reached me...surely, there must be a solution here for the greatest good of all involved.
hopefully, more will be along with their ideas and experience. that's normally the case here.
my prayers are with you,
naive