Hi, my baby is due in winter. I read that you recommend that babies arms be out of sleeping bags or if swaddling to use a light material such as cotton or Muslim. How can I keep my newborn warm enough at night in a house where we do not have access to heating if I am recommended to use light weight materials for swaddling? Thank you

Red Nose does recommend that a swaddle/wrap should be a light cotton or muslin material.
Wrapping is a way of settling baby & not meant to be used for warmth.
Wrapping can be a useful method to assist baby to settle and stay asleep as it reduces crying time and episodes of waking.
Use only lightweight wraps such as cotton or muslin (bunny rugs and blankets are not safe alternatives as they may cause overheating).
https://rednose.org.au/article/is-it-safe-to-wrap-swaddle-my-baby

Bedding for sleep

The key is to keep baby warm (or cool) enough so as not to overheat or have baby cold.
Red Nose provides the following information.
Dress baby and use layers as you would dress or use layers yourself: to be comfortable, neither too hot nor too cold.
Make up baby’s bed so baby sleeps at the bottom of the cot and the blankets can only reach as far as baby’s chest, ensuring baby cannot move down during sleep and get his/her head covered by bedding.
Consider using a safe baby sleeping bag (one with fitted neck, armholes or sleeves and no hood).
Dress baby for sleep and add/remove lightweight blankets to ensure baby’s back or tummy feels comfortably warm to the touch.
Remove hats, bonnets, beanies and hooded clothing from baby’s head as soon as baby is indoors
https://rednose.org.au/article/bedding-amount-recommended-for-safe-sleep

There is no accurate amount of bedding/blankets that it necessary for each individual baby.
It is important to ensure that bedding is safe = not too much/not too heavy/ not loose (to ensure baby’s head & face remain uncovered.
Red Nose recommend that rather than state how many bedclothes can be safely placed on a baby, parents can work out the amount of bedding to be used after considering these factors:

The room temperature where baby is sleeping.
How hot does the baby feel? A good way to check baby’s temperature is to feel baby’s back or tummy (don’t worry if baby’s hands and feet feel cool - this is normal).
Whether the baby has a cold or infection or another special need.
Consider how many layers that you as the baby’s carer are wearing comfortably.
https://rednose.org.au/article/bedding-amount-recommended-for-safe-sleep