Having cared for a total of TEN carees (!) I understand how torn you are feeling.
However, your daughter is going to need to learn how to manage on her own, and it's going to be a steep learning curve. She needs to find her way of dealing with things.
I'm in the New Forest, not too far from you, and it's easy to get to London on the M3 out of rush hour, and train travel is easy.
Why not arrange a carer for your husband for one day, to go and see the babies. Then do all the research you can about twins, recovery, domestic help, etc etc. Is there a twin club near her, for example?
What help does your husband currently receive?
Claiming Attendance Allowance?