Is this against building regs - stairs in bedroom?

[CatAndHisKit]

Just seen a house thats been a bit longer than usual on rightmove in the area I'm looking - nice 2-3 bed terraces sell like hot cakes there right now. It's a bit higher than my top budget so I didn't see it before.

Then I saw the catch - staircase from the main bedroom to the loft room which they call 'occasional room' yet house is liste das 3-bed.

Never seen that before actually, as staircase is at the end/corner of the bedroom that is over the passegeway with no door (but carpeted proper one, not a flimsy type). As far as I can see on photos, there is no door in the loft room where it leads to.
I can see that may people wouldn't like it in terms of walking through a bedroom, but is this againstt he rules and potenatially a huge headache / delays with lawyers / would need indemnity?

It would actually suit me as there is a private bedroom two, which is just ok size on the 1st floor, AND I'm hoping there may be a discount for that as this far I've been outbid on every house.
Yet really don;t want to pay for surveyor just to find out it's wrong - I can't afford to pay two lots of survey fees if I have to pull out!

Thanks in advance if anyone can advise on this!

Thank you so much for responses!

Good to know that the enforcement period of 12 months doesn't apply anymore. Obviously will haev to pay for structural survey which is not odeal (even standard one is 500 in the area), and if not ok pay again elsewhere.

Sounds like I wouldnt have to install firedoor/s.

Re flying freehold - the space over arch is part of the bedroom and no neighbour's room at the back - the shared passegeway is normal on all terraces I've viewed in the area so I doubt there would be a mortgaeg issue for anyone (?)

That's the point - for me it is a useable space and much needed, there won't be anyone else staying up there, it's not even a large loft room. I'll be using the 2d bedroom om the 1st floor for guests. Id be happ to compromise on this if vendor lowers the price - so it's not the privacy issue at all, just the liability, and also safety even though it looks like a quality job/finish but who knows.

All depends on whether the price can be right (as pp said, between the 2 and 3-bed price) and needs to reflect the full survey too.