I know we shouldn’t have bumpers or anything in the cot with bub but my baby keeps rolling and hitting her during the night. Is there a safe solution?

How old is your baby?
Is she still being wrapped/swaddled?
Does she wake when she hits her head?

When baby is learning to roll, it is particularly important not to have soft & padded items in the cot.

It is not uncommon for babies, once they are rolling to come in contact with the sides of the cot, hitting their head &/or with their arms/legs poking through the slats.
This does not usually last long, & the risk of injury is negligible.

United States Consumer Product Safety Commission data has shown that infants suffer essentially no long-term injuries from contact with cot slats.