Here's more detailed post for anyone who ever encounters something similar:
So the noise was actually from two separate problems, bad wheel bearings and the alternator.
For the alternator:
Someone here suggested it might have been the idler pulley, however the noise was much louder than any noise a bad idler pulley could have made: With the hood open I had to scream to the person beside me to be understood.
It was tricky isolating the noise to the alternator though, when looking at the engine from the front you could tell the noise was obviously from the side with the power steering and alternator.
Taking the belt off and turning all the pulleys manually didn't help as none of them seemed bad. When running the engine without the belt on the noise left so it was obviously something attached to the belt causing the noise.
With a stethoscope the sound coming off the alternator was just a little bit louder than the power steering, so I sort of took a chance by changing the alternator (luckily I was right!). Mind you I had two mechanics (friends) look at the engine too and neither of them was 100% certain where the sound was from, however they both guessed the alternator.
Changing the alternator was very easy, there's a video on youtube, but basically disconnect negative battery terminal, take off the belt, take off the lower pulley, remove two bolts holding alternator in, disconnect wires, take out the bad alternator, and repeat process in reverse order. No more noise!
For the wheel bearings, I changed the entire hub and it went surprisingly well, I had to get a 32mm axle nut socket (which for some reason didn't fit snugly but 31mm nut socket's don't exist apparently), I took off the wheel, caliper assembly, rotor. Then I took off the axle nut using a normal socket wrench, and a pretty long tube to give more leverage. Then I had to deal with 4 15mm bolts, went very well too. After that I spent about 10min. knocking at the old hub (I took off a little shield to get more whacking room). For this part I'd loosely put the axle nut back on to make sure you don't mistakenly hit the axle.
After that sand the everything down to make sure you have a clean surface, get the new hub on, put all bots back on, get the nut back on (I read you should get a new one but I put the old one back on), then rotor, caliper and wheel and you're all done.
