How to warm north east corner rooms?

Fire_Fox

Trickle vents in the windows wouldn't be sufficient to address that level of condensation, they are usually part of a ventilation strategy. And you do needa strategy, a damp area is unhealthy for occupants, for the building and won't feel warm.

You might consider a single room heat recovery unit. This ventilates at a constant low rate 24/7 year round AND conserve a good percentage of the heat. Or if your loft or other area is warm, a decentralised mechanical input ventilation unit (MEV). Consult a BPEC domestic ventilation installer for these.

An electric underblanket on the bed is a very cheap way to be toasty. An 'overnight' setting means it can safely be on all night. Also can be left on 'low' all day with duvet removed to air the bed (we all sweat lightly at night, and a slightly damp bed feels colder).

PasturesNew

Best place to start, that'll do something identifiable and give you at least "a better home" would be to invest (£100-150 max) in a little dehumidifier and plug it in.

If you can dry out that bedroom and the air then you're not causing more problems in the future, you'll be able to see the difference and that'll at least lift the spirits.

Air post-dehumidifier is allegedly easier to warm ... some science reason about water and holding warmth etc.

So, if you do nothing else, get researching a dehumidifier.