The regulations will only require the cables are to be made dead. This would include live and neutral cables. I would disconnect ever thing upstream of the switch and then terminate all conductors at the wall lights and at the switch together. You cannot plaster over the switch if conductors going to it are still connected to the live supply all live cable routes must be identified as per permitted safe zones. Standard metallic cable capping, does not qualify as mechanical protections.
Indeed it does make sense. The aim is to make sure it cannot accidentally come live. Plus with the any RCD installation in circuit, they can trip even if the circuit is isolated. So you are best disconnecting the neutral as well at supply side. As earth-neutral trips do occur.
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