Self-Employment Income Support Scheme
To apply go here, enter your Unique Taxpayer Reference, enter NI number.
Complete the personal details – full name, address etc.
You then need to add your Bank account details, then submit.
All done in about 5/6 minutes.
https://www.tax.service.gov.uk/self-employment-support/enter-unique-taxpayer-reference
Thank you to Lee Hendrick McCrone for finding this.