My baby has started to roll at four months old. We are now transitioning him out of his swaddle bags to have arms out. We know the next step is to move him into his cot but are worried as we can’t fit a cot in our bedroom. We are wondering which is safer re: sids risk, putting the baby in a room by himself in a cot or putting a portacot in our room next to the bed for the next few months so he is close by (understanding that safety standards are lacking in portacots). Please help, we are worried what to do! Thanks.

Red Nose recommends that parents room share for the first 6 to 12 months.
Room-sharing with a baby has been shown to reduce the risk of SUDI.
Red Nose therefore recommends sleeping with a baby in a cot next to the parents’ bed for the first six to twelve months of life.
https://rednose.org.au/article/room-sharing-with-baby

Sudden Unexpected Death in Infancy (SUDI) occurs in the first 12 months of life. Hence the reference to 12 months.
However 90% of deaths occur in the first 6 months - hence the reference to 6 months.

Red Nose also has the following information:
Parents are not expected to observe their baby constantly. If your baby is sleeping in a separate room check baby regularly to ensure that the baby remains on the back and the head and face remain uncovered (as baby grows beyond 5-6 months they will move around the cot and roll over; settle baby to sleep on their back but let them find the sleep position they feel most comfortable in.
A safe cot and safe sleep environment is still necessary for babies older than 5-6 months)
Have a look at the article https://rednose.org.au/article/room-sharing-with-baby
for further information & link to the references to support the information.