Seen the other posts, one thought if you do stay...
- If he will not spend more on heat input
- Will he spend on insulation?

- Do you have loft insulation?
- Do you have cavity walls that can be insulated?
- Would he spend money insulating the living room?

B&Q do four extruded polystrene 1200x600mm 50mm slab for £19, various
builders merchants do Celotex 25mm for £14 and 50mm for £20 2400x1200
(celotex is about 50% better). It does not cost much to insulate the
outside walls of a living room such that you can reduce heat loss from
1000W to 100W. That means you pay no more for heating but are
monumentally warmer re 1) higher internal temperature 2) eliminating
plunging cold draughts 3) reducing damp.

Some people can be SO OBSTRUCTIVE, hilarious you are having the
problem with a man when I have it with my mother! Insulation is
winning her over, and she has a lot more problems with her house than
yours (lived in it 60yrs, nothing done really so down to me when time
to progressively and "keyhole surgery" improvements).

For a good wallpaper that is cheap, textured, not offensive, easy to
paint try Graham & Brown "bobble". It is a small random raised-dot
pattern which actually works very well. Easy to get perfect on the
wall, about £6/roll (dozen rolls for £42 delivered as I recall).