My 5 month old is a side sleeper and has just started to roll, I would still like him in our room as his room is down other end of the house, is a portacot suitable for use for a couple of months until he is ready to move to his room?

Red Nose recommendations are to “always place baby on back for sleep” not baby must always sleep on their back.
https://rednose.org.au/article/red-nose-safe-sleeping-recommendations

Most babies will be rolling over by 4- 5 months. Some earlier, some later.
This is very normal as babies grow & become stronger.
Many babies then prefer to sleep on their side or tummy.
This is not something that needs to be stopped. It is important to make the “new” environment as safe as possible.
https://rednose.org.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over

How does he go with tummy time when awake?
Increasing tummy time when awake is important to build upper body strength to roll well (both ways)
Is he rolling from tummy to back during tummy time, holding his head well &/or reaching for toys?

It is important for your baby to be sleeping in a cot now & to cease swaddling/wrapping.
Babies need to space of a cot & arms free to roll well & confidently.

Many parents are unable to room share for all sleeps..
Some parents find a portable cot (that meets Mandatory Standards) is helpful to continue room sharing till 6 mths.
If using the Portacot, check that it meets the Mandatory Australian Standards & that the locking mechanism & mesh are in good condition.
Use only the mattress that comes with the cot & do not add an other mattress or padding.
https://rednose.org.au/article/portable-cots

If/when you do move him to his own room ensure doors are open & you are able to hear him
When you wake up during the night, check on him.
No parent is expected to sit up all night/day watching baby.

Important to maintain all of the rest of the safe sleep recommendations, in particular:
  always place baby on back,
  keep head & face uncovered (nothing loose or soft in the cot)
  provide the safe environment (cot with firm, flat(not elevated) mattress.