If you want to do paid work in the UK you need a NI number. To get one you can EITHER:

Phone the NI applications line. Details here: National Insurance and Tax Guide 2019-20

OR  Book a space on one of the National Insurance Processing Days (15^th 17^th and 24^th of October). To do this, go to the Events tab of MyCareerHub. Then type National Insurance in the search box and click the green Search button to see the times. When you’ve chosen one click on its heading to see more information. Make your booking by clicking on the blue Book button.

Please be sure to cancel the appointment if your circumstances change, so someone else can book it. There’s always heavy demand for these sessions.

You won’t be given your number immediately but it will speed up the process.