Get information about the "qva_iwxxm" {collectionId}. It is the ‘source of truth’ to check which data has been generated and is ready to download. This is the endpoint that you can query to find out the applicable "volcano_id" for which forecast data is available. You can then use "volcano_id" to build your API request.
Response is a JSON file.
Url
https://gateway.api-management.metoffice.cloud/vaac-london-qva-products-data/1.0/collections/qvaci_iwxxm
Resource Type
REST_RESOURCE