My 7 week old baby is quite a wriggler in his sleep, he is often against the side of the mesh in his bassinet when I wake to feed him and this morning he had gotten himself sideways across near the bottom of the bassinet. Currently in love to dream arms up suits. What do I need to do to ensure safe sleep, does he need his arms out incase he accidentally rolls?

There is no need to stop your baby from wriggling & changing his position, but it is important to make his environment safe in light of what he is doing.
Many babies will wriggle & change position (like you describe) at a young age.
While most babies do not roll intentionally till about 3 months, some do roll early.
He may be one of those.

Also, some babies just do not respond well to wrapping & like their arms free.
Often these babies like their arms free or like to touch their face or suck fingers & will wriggle to get free.

It is important that you move him from bassinet to his cot & cease wrapping as he may be be attempting to roll.
Baby needs arms free & the space of the cot to roll safely.
Once baby is showing signs of being able to roll, it’s time to move baby to a safe cot – this is usually around four months, but it will depend on your baby.

https://rednose.org.au/article/bassinets

How does he go with tummy time when awake?

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 tummy.
Once he is rolling (or attempting to) it is important to make the environment as safe as possible for this to occur.
Continue to place baby on the back to sleep.
Ensure cot mattress is firm, well-fitting & flat.
Ensure there is nothing loose or soft in the cot.
Preferable to use a sleeping bag when rolling that has appropriate size neck & arm holes.

Red Nose has the following information when baby is rolling.
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 lambswool, 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

Do not use any devices designed to keep baby in a particular sleep position.
https://rednose.com.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over