I'll be happy to walk you through the process of viewing your submitted FPS to HMRC.
If you're using the Standard payroll, you can view your submission by going to Taxes and selecting Payroll Tax. All your previous filings are under Filed Forms. Each card shows the name of the form, the pay period it was sent, the status of the filing, and the date submitted.
And if you're using the Advanced payroll, you can check it by going to Payroll, clicking Reports, then going to RTI Submission Messages.