How to check if HMRC has received my submission of Paper (Self Assessment) Tax Return? Thanks.

I posted my Paper (Self Assessment) Tax Return to HMRC (BX9 1AS) on 6th Sept. May I ask how to check if HMRC has received my submission of Paper Tax Return? Thank you.

Hi,
As we would need to access your records to answer your query, you will need to contact our Self Assessment team for advice.
Self Assessment: general enquiries
Thank you.