Hi @Alfie wilkins  
Deny” error when creating an Azure Static Web App, it means an Azure Policy set by your organization or subscription administrator is blocking your request. These policies determine which resources you can create, their locations, and allowed settings. 
Check the Activity Log, open the failed event, and view the JSON details to identify the policy causing the denial.
Visit Azure Policy Compliance to find the specific policy.
The restriction may apply to the resource type (Static Web App) or the region.
Contact your admin to request access for Static Web Apps or select an approved region.
If you are working under a managed/company subscription, you may need to use your personal Azure account to avoid these limits.
Understand the Deny effect in Azure Policy
Microsoft Q&A – Static Web App creation denied by policy  
Let me know if you have any further assistances needed.