We would need to know what is your style? Color and fabric preferences? What will the second bedroom be used for? Pictures of what you already have (and want to keep) would be most helpful, as well as pictures of the flat.

Eventually when you come to resell, a pool is an added plus. But for your own purposes, emptying the pool and adding a deck over it with a hinged door and steps placed below would be great for storage (as per option b but bearing in mind you could revert). All the best for your lovely new home.

Hello aju007, Be certain that the structure is sound prior to placing anything on the roof. After that has been determined, you might think about using it for either a deck with cozy chairs and table or a garden area. A few Houzz examples: Best of luck and please let us know if we can be of additional assistance, Elizabeth Cabell, ASID, CID Cabell Design Studio

Hello Sagar, This space is sufficient for a bathtub in a bath. Thanks, Nitin CORNERSTONE DESIGNS, Bangalore