Removing condensation from headlamp

My nearside headlamp must have a gap in the seal as I have a fair amount of condensation build up.

This was enough to fail the MOT as it restricted the light being output by the bulb (not noticable when driving though!).

The headlight unit has two internal enclosed focusing units for the bulbs which I can only just access, but I can't get to the glass at the front where the moisture is.

Any ideas as to how to clear the moisture? I think an entire replacement head unit will be over £100 including the labour.