If you accidentally used self-raising flour instead of plain flour and already added baking soda and bicarbonate of soda (baking soda), it's possible that your cake may rise more than intended. Self-raising flour already contains a leavening agent (usually baking powder) to help the cake rise, so the additional baking soda and bicarbonate of soda might make it rise even further.
The excessive leavening agents could result in a cake that rises too much and potentially collapses or has an uneven texture. However, it doesn't necessarily mean that the cake is completely ruined. It might still be edible, albeit with a different texture and possibly a stronger taste.
If the cake has not been baked yet, you can try to salvage it by adjusting the other ingredients to compensate for the extra leavening agents. You could add more plain flour to counterbalance the self-raising flour and reduce the amount of baking soda and bicarbonate of soda. The exact adjustments would depend on the specific recipe you are using, so it's challenging to provide precise measurements without knowing the details.
If the cake has already been baked, there's not much you can do to fix it at this point. However, it's worth tasting it to see if the flavor and texture are still enjoyable. You might discover that despite the alteration, it's still a tasty treat.