Is it permissible to say, "Glory be to You, Allah, You are the Creator without a creator," and is the one who says it sinful, and what are the implications if that is the case?

If the intent is that you created everything and are not created, then you are Allah, the One, the Self-Sufficient, Who neither begot nor was begotten, nor has there ever been unto Him anyone equal. This is a truthful statement that does not necessitate repentance or seeking forgiveness.