I would also add the following:
The fact you get really bad condensation as well (I assume on windows...are they upvc or single glazed) I would begin to suspect that possibly self inflicted condensation is a contributing factor as well.
Please read this post which I recently responded to extensively and read the manuals on the links.
http://www.diynot.com/forums/building/condensation.386014/
You need to possibly ventilate your property much more than you may realise or expect.
Old properties were not made with central heating in mind and were made to be drafty and not air tight. That way the damp air circulated and escaped.
With modern drive towards insulation... upvc etc. there is more "air tightness" there is moist air and no where for it to go (this is made worse by central heating heating up and cooling down the room)....so it goes on to the nearest cold surfaces....your windows and especially that lovely cold single skin wall.
So you really need to ventilate a lot more. Keep trickle vents open (if you have them), windows open on night vent if your upvc has it (locked but open a crack), or just keep them open a crack.
Extractors in bathroom and kitchen (preferably with humidistat). Do not dry clothes on radiators!!!! Ensure dryer is vented outside and the extraction tube is not leaking and the fluff is removed regularly. Keep doors to kitchen and bathroom shut when in use! If you dont have a dryer...go to the laundrette.
If you have central heating, rather than having it go on and off. Try to keep a lower more constant heat to keep the room warm...
I am not saying this is the only cause... but is very likely to be a contributor..
People do not realise most of the time how much moist air is produced in a house on a daily basis, and that more often than not, they are the cause of the condensation...