You need to know what? You should only need a licensed electrician to install the lights and fans.

It would be real handy to know what type and style the customer wants installed.

If the exsiting structure doesn't currently have ceiling lights or fans, and there is no access from above (ex: attic space), then you may want to find a good drywaller. This should be all you need. Let the EC do an estimate, and ask him or her if you will need a drywaller.

Just my .02

I'm not sure I understand the question.

Are you asking, if someone hires an electrical contractor to deal with lights and fans, what other types of contractors might they also need?

If so I agree with Washington.

Are you asking, if someone hires an electrical contractor to deal with lights and fans, what other types of contractors might they also need?

This is how I read the question.