4. Create test business

Creates a self-employment business for in the sandbox (auto-deleted after 7 days).

{ "typeOfBusiness": "self-employment", "tradingName": "Ida Izzard Plastering", "tradingType": "Plastering", "businessAddressLineOne": "4 Downing Street", "businessAddressLineTwo": "Newport", "businessAddressPostcode": "TS25 1PA", "businessAddressCountryCode": "GB", "firstAccountingPeriodStartDate": "2026-04-06", "firstAccountingPeriodEndDate": "2027-04-05", "accountingType": "CASH", "commencementDate": "2020-05-01" }