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If you design it from scratch and with nice bits then it will be great. Separate bath and shower are useful and it's not like you need to break dance in the middle of it so if it's compact then fine. Storage would be the thing that I was thinking about, if you make the space work hard in terms of where to put towels, spare loo roll, toiletries etc and keep it out of sight then the space will feel bigger.
Maybe move the rad behind the door and then you could have a full heigh storage on that wall instead
Deffo bath under window.
I’d go option 1 personally