In response to your replies,
H is controlling, sulky, bit of a Disney dad and I feel more like his mother and housekeeper than his wife.
If I'm honest, I don't love him and haven't done for some time. We talked again and I brought up so much about our past that I know I have been bottling up. As did he.
Now I know that there is much resentment from us both and I know we cannot make this ok. So no, I am not giving him false hope as we now both know it is truly over 
We have decided that we will continue to live in the same house until dd at least has a diagnosis. I am aware that this may take some time. But we seem to be getting on ok, and already h has stopped relying on me to do tasks for him.
We enjoy co parenting, although I am pretty sure that he won't have care of dd on a totally equal basis, but that is ok as long as dd is happy and secure.
No, we haven't a spare room that we can use as a bedroom, but with dd being awake in the night fairly regularly we often have a bed swap at some stage so think we can continue as we are for now.
I realise that h is more than happy with this arrangement as it is the easy option for him. But I am focused on getting dd in track so that she will be in a better place for when we do tell her about the split. It would be totally unfair on her to tell her at present.
I think it will be a bumpy ride when we do split. I told h that I had been thinking about looking for a rented property, and he implied that we can be friends as long as I am still in the house, I think it will be different if and when I move out with dd.