The Alpkit Soloist looks tempting for low level use, only 1.2kg, quite a bargain at £125 - but it is on back order.
Traditional closed cell foam mattresses are dirt cheap, indestructible and lighter than blow up mattresses - but obviously less comfortable. My cut down Karrimat from the 1980's only weighs 200g.
As suggested, a meths stove is lighter and very cheap, but methylated spirits has a lower calorific value than gas, and can be difficult to obtain en-route, so I would not recommend for a longer trip. Not sure that I would want to ditch the stove altogether on a longer trip, especially over winter.
Headtorches - get a bottom of the range Petzl Tikkina - inexpensive, light, bombproof; will not let you down.
Cut down on the non essentials - You are never going to be far from civilisation.
Good luck on your travels!