Separate fuses per phase are only a real issue if it can lead to a 3P motor limping along on a single phase and overheating, possibly becoming a fire risk. Normally the motor overload protection should stop that anyway and it is not a likely problem for such a property.
As above, I would follow the BPG#3 guidance which, though less readable now, is still C3 for no RCD in low-risk areas (i.e. typically indoors) and C2 for high risk areas (like out doors or in bathroom areas, etc.)
Lights all one one fuse is a bit dumb, but if loss of light is a serious risk anywhere then having emergency lighting is far more important as it also deals with a power cut.
I don't like SY cable but it is OK for indoor use (not UV tolerant) where the braid is not actually needed for penetration protection (not rated to clear OCPD). Its not really a very useful situation, but not specifically bad if those are not needed. SWA or Flexishield/BS8436 are cables that meet the penetration aspect, though for the foil types it is often only to a modest OCPD let-through like 20A MCB or similar.
As above, I would follow the BPG#3 guidance which, though less readable now, is still C3 for no RCD in low-risk areas (i.e. typically indoors) and C2 for high risk areas (like out doors or in bathroom areas, etc.)
Lights all one one fuse is a bit dumb, but if loss of light is a serious risk anywhere then having emergency lighting is far more important as it also deals with a power cut.
I don't like SY cable but it is OK for indoor use (not UV tolerant) where the braid is not actually needed for penetration protection (not rated to clear OCPD). Its not really a very useful situation, but not specifically bad if those are not needed. SWA or Flexishield/BS8436 are cables that meet the penetration aspect, though for the foil types it is often only to a modest OCPD let-through like 20A MCB or similar.