My baby started rolling from back to front only, just over two weeks ago. He’s now 18 weeks and still only rolling one way. We give him plenty of tummy time during the day and he can stay playing on his tummy for very long periods at a time, can use his arms to push and hold himself up, however he’s not yet able to roll from tummy to back. He keeps rolling in his sleep, and we keep waking and attempting to roll him back to his back, however every time it ends with him screaming and crying, and we end up having to get him out of bed to feed and calm him. A lot of the time when we then put him back down, he’ll automatically roll again. We’re at our wits end. Is it okay to leave him on his stomach if he’s rolling there, considering how much neck strength he has?

What you are describing is normal development.
Most babies will be rolling over by 4 - 6 months…. some earlier
This is very normal as babies grow & become stronger many babies then prefer to sleep on their tummy, & often don’t change from that position.
This is not something that needs to be stopped, but it is important to make the environment as safe as possible for this to occur.

Always place baby on their back to sleep.
Transfer to cot if not already.
Ensure cot mattress is firm, well-fitting & flat.
Ensure there is nothing loose or soft in the cot.
Use a sleeping bag now that has appropriate size neck & arm holes if appropriate….. ie with arms out.

It is essential to discontinue wrapping as soon as baby starts showing signs that they can begin to roll..
https://rednose.org.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over

Red Nose now recommends that a wrap should be modified from about 3 months to allow baby’s arms to be free in preparation for rolling

Red Nose has the following information now that your baby is starting to roll.

Give baby extra tummy time to play when awake and supervised as this helps baby to develop stronger neck and upper body muscles which in turn enables them to roll back over.
Make sure that baby is on a firm and well-fitting mattress that is flat (not tilted or elevated).
Make sure that baby’s face and head remains uncovered (do not use lamb’s wool, doonas, pillows, cot bumpers or soft toys)
As babies grow and develop they become very active and learn to roll around the cot.
At this time, continue to put them on the back at the start of sleep time, but let them find their own position of comfort
By this stage it is not necessary to wake during the night to turn baby over to the back position
https://rednose.com.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over

Do not use any devices designed to keep baby in a particular sleep position.
https://rednose.org.au/article/is-it-safe-to-use-products-designed-to-keep-baby-in-a-particular-position