Removing steering column to access heater matrix?

[8Jb9]

I've discovered that the heater housing is wet at the bottom, and when I start the car I have a whiff of very humid air from the vents (fogs up if the conditions are right). While it might just be the O-rings I've decided to replace the whole unit if I can access it.

It's a LHD car, so I can't do the glovebox-trick. How would I go about removing the steering column in order to pull out the heater? Or is there a slightly less painful way also for LHD?