As of 13th May, the Coronavirus Self-Employment Income Support Scheme (SEISS) is now live.
You can claim from this scheme if:
If your application is accepted, the amount you will receive will be based on your average trading profits over the last three tax years. It will amount to 80% of your average monthly trading profits, paid out in a single instalment covering 3 months, and will be capped at £7,500 altogether.
First, you need to check if you are eligible. You can do this here. Note: you will need your Self Assessment Unique Taxpayer Reference number from HMRC to do this.
If you are eligible, you will be given a date from which you can claim.
On or after that date, you can make your claim here.