I have a bubba blue sleep pouch for a cot. It’s red nose approved but goes up to 12 months. Is it safe to use once baby is rolling?

If there is any risk to baby of rolling & getting stuck within the pouch, or bedding covering head/face, then the product may not be suitable for a baby who is rolling.
Same as for traditional top sheet & blanket, if baby is rolling it may be preferable to not use any bedding, to reduce risk of head/face covering, but to use a sleeping bag (arms out) with no bedding.
You can always add extra layer of clothing to baby during cold weather.
https://rednose.org.au/article/how-to-dress-baby-for-sleep