chore: Add changeset

.changeset/popular-laws-thank.md

@@ -0,0 +1,15 @@
+---
+"@guardian/cdk": patch
+---
+
+fix(experimental-ec2-pattern): Create Policy first
+
+When deploying Prism with the `GuEc2AppExperimental` for the first time, the deployment failed with the cloud-init-output logs stating:
+
+```log
+An error occurred (AccessDenied) when calling the DescribeTargetHealth operation: User: arn:aws:sts::000000000000:assumed-role/prism-CODE-InstanceRolePrism/i-0cee86d64de253ca4 is not authorized to perform: elasticloadbalancing:DescribeTargetHealth because no identity-based policy allows the elasticloadbalancing:DescribeTargetHealth action
+```
+
+This suggests the instance update was started before the policy was created.
+
+Make the ASG depend on the policy that grants these permissions to resolve, as CloudFormation creates dependencies first.