I'm a senior and there's no Finalise button

What you're seeing. You can open a journal marked Awaiting Review but there's no way to sign it off.

Why it happens. Finalising is manager-only. Seniors and deputies do not hold it, and it cannot be granted for one day or one journal. A senior otherwise has the same record permissions as staff.

How to fix it. Your part is finished when the day is submitted for review. Ask the manager on duty to sign it off.

Who can fix it. Your manager.