I've recently purchased a townhouse which is split over 4 floors (ground floor, 1st floor, 2nd floor and a loft conversion). The building survey has recommended that fire doors are installed in the property (it looks as though the previous owner had these removed at some point and installed with cheaper doors) which we're looking in to at the moment. The survey has recommended that FD60 fire doors are installed but when trying to scout out our door options, these seem to be more common in commercial properties. Would FD30 fire doors be sufficient?

Nothing in Building Regulations or fire safety guidance for your situation requires FD60 doors, FD30 would suffice.