(Power)steering failure

[dangerdred]

Apologies...it's a little long.
On my way home tonight, I was doing a right-hand turn to merge out onto a dual carriageway, and as I turned to join the initial merging lane, I turned the steering wheel and the next thing the wheel wasn't turning and the car was going to go straight out into the traffic. I braked hard and luckily there was nobody behind me. My power steering was gone completely so with literally all my strength, I managed to turn the steering wheel to straighten the car up and roll it along the merging lane a bit towards the hard shoulder with my hazards on. I killed the ignition and started again but it was still the same. I wasn't far from home but as I started driving down the road all the windows suddenly fogged up as if something was going on with my AC.. On the way, any 90 degree corner I had to take I had to take it really wide, and even still would end up the far side of the road as I came around. Thankfully I got it home in the end and when I turned it off and got out, all the fans under the bonnet were going like billio. I went into the house and came back out 5 minutes later to do a scan. The battery had gone right down with 1 bar on the MMI screen gauge so I thought maybe the fans had depleted the battery. Anyhow, are fans any clue as to what's going on with my steering? When I was doing the scan I inadvertently started the engine, but when I saw it was charging the battery I decided to leave it run. Then I noticed there was a loud whirring sound coming from under the bonnet and when I lifted it, it sounded like a fan was rubbing off something, but as I shone my light in I could see the belt going around and everything looked OK except for the noise. Could it be a seized pulley or something? I'll try and have a better look tomorrow in daylight. Any ideas?