I have not had focused discussions on this specific aspect of the flooding that occurred in Gloucestershire.
The Environment Agency has produced guidance on the use of sandbags with the Local Government Association. Sandbags must only be seen as an emergency response. There are more robust solutions that resist flooding of individual domestic properties such as flood-boards and airbrick covers.
I understand from the Environment Agency that approximately 2,500 sandbags were available in Tewkesbury and all were deployed.