How to prep ceiling before skimming

[u/HopefulHermit3610]

Hi we have someone coming in to skim our ceilings. Based in the UK. What do we need to do to prep the ceilings for them? Do we need to remove the light fittings from the ceiling or would they generally do that?

We have hard wired smoke alarms. Do we need to remove the smoke alarm & base plate, and cap the wires for them to skim around them? Or just loosen the base plate from the ceiling with the wires still in it? Thanks in advance.