My baby is 7.5 months old and is usually a great sleeper but after starting daycare she has been up most of the nights and is seeking constant comfort. We are trying to introduce a comforter (a teddy) and I just wondered at this age would it be safe for her to have this in the cot with her at night ?

Red Nose recommends withholding any soft toys or comforters for babies less than 7 months of age, as they may increase the risk of suffocation.
Keep soft toys out of the sleeping environment for babies under seven months of age because they may cover the nose and mouth and interfere with breathing.
The risk posed by suffocation by the presence of soft objects in the baby’s sleeping environment outweighs any benefit to the baby from a soft toy. It is therefore advised not place soft toys and other soft objects in the cot for babies under seven months of age.
Seven month old babies are more likely to explore objects in their sleeping environments than younger babies. Some babies over seven months of age may appreciate a small object such as a soft toy to provide comfort and connection (transitional object1) during times of separation from their parent.
https://rednose.org.au/article/soft-toys-in-the-cot