Can I legally sell my house as a 3 bed with moveable wall system in place, or do I have to have a fixed stud wall?

I own a two bed property which originally was a three bed (a solid stud partition wall was removed between master and box room by previous owners). I want the option of creating a third bedroom by using an acoustic moveable wall system (like in an office to separate large areas into smaller rooms and vice versa). Each solid panel consists of a metal frame which is covered with a 16mm high density board and infilled with the required acoustic baffle to match the acoustic rating of up to 59 dB. By doing so it gives me flexibility to have a large two bed or a smaller three bed layout. My question is would this moveable wall system comply with building regulations to the point where I can sell or rent my house legally as a three bedroom house? (It's worth noting the third rooms has its own door, window, lighting, heating etc.)