I'd go with the opening in the open plan side as well (green door opening).

Yes I can make that stud wall longer to accommodate for a 800 wide hidden door and 800mm opening. The benefit of not having the hidden door is that we can make the 800mm tall unit as storage rather then a access

So many decisions to make and still not even set on the idea of either having a peninsula

or the 2 seater island

Have you had a professional kitchen design? That might help clear up and visualise which options work for you