I've got some steps on how to retrieve the past Real Time Information (RTI) submission to the HMRC, mizzbrownie.
May I know what payroll subscription are you using? You can access the RTI you filed in QuickBooks Online, however the option to show the receive date is unavailable. You'll want to access the HMRC website to see the time on when it was received by them.
If you're using PaySuite, just go to the Gear icon on the top menu and choose Employer Settings. From there, you'll see the reports that you sent and the date on when you submitted it to the HMRC. For Standard payroll, you can click Taxes on the left menu and select Payroll Tax. Then, look for RTI you've submitted.
If in the future you'll encounter an error when submitting your RTI, please refer to this article to troubleshoot the issue: Common HMRC RTI Error Messages for Payroll.
To learn more RTI, you can check out these articles:
Feel free to reply to this post if you need a hand filing your year-end forms. I'll be here to ensure your success in processing them.