I do agree with protectthehornet's post 3 up, except for them "drifting off the localizer".
Seems to me, they had the (or both) autopilots coupled, and the signal got bent by the departing aircraft. The a/p kept them dead on a bent signal, causing a sverve or something, and as they saw at least something of the Rwy, lights or whatever, they tried to recover.
It can be very disorienting to fly in fog with little reference to the ground. (Believe me, I get the feeling regularily doing my manual HGS CAT IIIa).
It's just a guess, though. We will see what the report says...
Nic
PS.: Hey Micky, should I be speaking Dutch...?