Hi there, Our baby is 3 weeks old, from early days we observed our baby will roll onto their side to sleep in their bassinett. We place our child on their back to sleep in swaddle sleeping bag and tuck a light blanket over them to ensure they are snug, however they still manage to roll onto their side. We continue throughout the night to correct their positioning and place him back onto his back, however you guessed it after sometime he somehow manages to roll himself back onto his side. We are worried now that when he his rolling that his wriggling his way closer to the edge of the bassinett and potentially pushing his face close or up against the edge/wall of bassinett. Could you suggest any tips on preventing him rolling or point us in the right steps to take next. Thanks

Most babies do not roll to tummy intentionally before 3 months; however, some babies do roll or wriggle, especially to the side, at a very early age. This is not unusual.

Some babies do not respond well to wrapping/swaddling & prefer to have their arms free.         
Some babies like to touch their face or suck fingers when settling.
You could try settling him without any swaddle, or wrap with his arms out. (as for 3 mth old)

https://rednose.org.au/article/wrapping-babies
Red Nose recommends using a light cotton or muslin wrap rather than swaddle suit like the one you are using.
Did you try a muslin wrap before using the swaddle suit/bag?

He may be more settled in a cot for all sleeps rather than a bassinet.

Have you commenced tummy time yet when awake?
If not, we recommend that you commence tummy time to help build upper body strength.
https://rednose.org.au/article/tummy-time-is-good-for-baby-because
Always place baby on the back for sleep.

You are not expected to wake during the night to keep checking on him.
However, there is nothing wrong with rolling him back if you see him on his side.

Red Nose does not recommend the use of sleep positioners.
Red Nose does not recommend positional products such as anti-roll devices and items that fasten a baby into a sleeping position.
Products that restrict the movement of a baby or a baby’s head should not be used.
https://rednose.org.au/article/is-it-safe-to-use-products-designed-to-keep-baby-in-a-particular-position