Need to 'create' a nursery from a large inner hallway. Advise pls, ESP about partitions

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We live in a lovely garden flat, but and it is a big BUT, only two bedrooms and I am expecting another baby.

Our toddler son sleeps very well and I absolutely do not want to disrupt this. We do have a large inner hallway, which is used as dh study ATM. He said that he will move his desk into our bedroom so we can make this a little nursery for the baby. It would be nice, esp as right outside our bedroom. The hall is big enough that we could section off a bit for the nursery, and it would still work as a hallway I.e. we would not need to go through the 'nursery' in order to go through.

Any suggestions at all as to how we could do this would be hugely appreciated. Anyone else divided a room? We do not want a permant wall there (it absolutely would not work). Instead we are looking for a decent partition or similar, preferably sturdy, slid and with acoustic reducing features.

It is a big ask! Thanks in advance. Budget of £750.

If you don't want a permenant something industrial might work. Like a concertina effect partition. They would be used in schools too. A stud wall would probably look better though and could be removed afterwards.

Would a large bookcase (facing into 'nursery' work as a partition? Then you have something non-permanent and storage for LO. Oviously it would need to.be slim.enough to fit a gap to walk through (wouldnt be sound proof tho).