Legal requirements as to light fittings

A neighbour is moving back to the UK and has asked what the legal requirements are regarding light fittings when leaving the house. I have told her I think as long as you leave a pendant with a bulb in the ceiling where any other fitting was and any wall lights will need to have wall light fittings on them and not bare wires, that meets the requirements. She insists she has to buy new lights and not just leave a bulb on the ceiling, who is correct?

When we moved here is was a dark April evening, not one light bulb in the house and bare wires everywhere! It seems rules may not apply to some!

Many thanks