Registering for self assessment - form not visible on personal tax account

I registered last week but there is no record of this on my personal tax account and I didn't screen shot the page before closing it. The deadline is 5 October - how can I prove it has been submitted in time? Should I have received an acknowledgment? Thanks.

Hi ,
 

If you have registered correctly, you should receive your UTR and confirmation of your registration 3-4 weeks after the date you registered. If you have not received confirmation after 4 weeks, contact us by webchat or phone via : Self Assessment: general enquiries and we can register you  . Thank you .