Hi, My son is 5 months old and is outgrowing his cradle. I’m not ready to transition him to the nursery and would like to keep him in my room until he is a year old. I can’t move his cot into my room so I wanted to know if it’s safe/recommended for him to sleep in the portacot overnight for a few months?

Bassinets are usually only suitable for use for baby for the first few months.
https://rednose.org.au/article/bassinettes
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/bassinettes

Product Safety & Red Nose recommends that a portacot is only used as a temporary sleep space.
Folding cots should only be used as temporary sleeping facilities. They are not suitable for long term sleeping arrangements (no more than a few days). These cots are subject to more wear and tear due to folding and are generally less robust than permanent sleeping enclosures such as household cots.
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/folding-cots
https://www.productsafety.gov.au/standards/folding-cots
https://rednose.org.au/article/portable-cots

It would be preferable that he is in a household cot, as they are sturdier & safer for long term use, particularly as baby grows, becomes more mobile & is sitting/pulling himself up on sides of cot.