power is usually last from my experience
when you hear the fans running then you are very close to available - mine was within a few days of fans being activated
Just thought I'd add a little light on the situation. I had an email from the BB4S team at the end of June. They confirmed the cabinet was stood and powered and was now just awaiting network connection and final copper connection.
The fact you have heard the fans running when you passed does confirm this.
The fact you have seen a guy laying the fibre cables is a good sign and should mean that we are not too far away from receiving fibre.
The estimate from the BB4S team was autumn.
Last thing you'll see before going live is a network guy with a laptop commissioning the cab (if your lucky enough to catch him at it).