Hi,
If your bank interest is less then £10,000 then this will not be criteria for Self Assessment.
If you registered and a Self Assessment UTR has now been allocated you would need to contact HMRC to review if tax return is needed. You can check if you meet criteria here:
Check if you need to send a Self Assessment tax return
Self Assessment: general enquiries
If you do meet other Self Assessment criteria and the Self Assessment is issued late then you will have 3 months and a week to file the tax return before late filing penalties are due.
Thank you.