Jasper Teddington

We are in the process of buying a three story Victorian townhouse that has had an infill extension of the old kitchen in 2013. This kitchen is open plan with a dining room, but the main staircase of the house enters directly into this dining room (no separation from kitchen). None of the bedrooms have fire doors and it was always three stories, it has not been loft converted. The extension has a certificate of completion stating that it conforms with building regulations, but we are concerned this is because the work didn’t make the fire safety any worse than the original layout and so it passed on a technicality because B regs aren’t retrospective. As far as we know there are no further mitigations presently (sprinklers etc.) but would definitely add wired alarms. We don’t think it’s practical to seal off the kitchen from the staircase/diner. How concerned should we be about both fire safety and resale, given the work appears to have been completed correctly but the set up is far below modern regulations? Should this be a deal breaker? Thank you!