Hi there, @t_fox-live-co-uk.

Thank you for posting here in the Community. I can provide some information about adding an employee in QuickBooks Online Advanced Payroll.

Yes, it's possible to add a worker without the information you mention above. If the National Insurance (NI) number for the employee is not available (or the employee is exempt from supplying a NI number), click the 'NIN unknown' box.

Here's how:

1. On the left navigation bar, click Payroll.
2. Click Add Employee.
3. Fill in the necessary information.
4. Under Tax and NI Details, search for the National Insurance Number field.
5. Put a checkmark on the box beside NIN unknown (NINO). 
6. Proceed until Finish.

For more information, as well as how to enter personal and employment details, I recommend the following article: Adding an employee in QuickBooks Online Advanced Payroll.

Feel free to hit that Reply button if you have additional questions. Have a great day ahead.