Hi Christian,
Please carefully follow my instructions below to create a new Service and subscription limits (quotas) request to allow access to deploy Azure SQL Database Managed Instance in UK West. Note that some subscription types (e.g. Free, Student) do not allow quota increase.
1. Navigate to this link to start the process:
https://portal.azure.com/#create/Microsoft.Support
2. Enter quota in the box and click Go
3. Select Others / Service and subscription limits (quotas) and click Next
4. Click Create a support request button, as shown
5. Select Issue type: Service and subscription limits (quotas), Subscription, Quota type: SQL Database Managed Instance, click Next
6. Now you should be on Additional details tab. Click Enter details
7. Select (Europe) UK West for Region, enter number of Subnet and vCores you are requesting in New limit column and click Save and continue
8. Finish filling out Additional details tab, click Next, review and click Create. You should receive an automated email within a few minutes.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP