My survey says I should install vent in bedroom & extractor fan in shower room

The wiring to the fan and fitting of it is an electrician and they may also do the hole/method to extract and the cover on the outside (depending on complexity) - sometimes a builder does that part so its all down to who you use to be honest. The one thing you should certainly do is use an electrician for the electrical works and with the right credentials to certify it. Cheers, Martin

I always do everything when I fit a fan. As I have diamond cutters.