margaret
Not sure what to suggest
as it could be a bit of a Catch-22.
Several members have reported problems, where another doctor has filled in the info request while their normal foctor was absent, so it might be worth you contacting your practice to ensure this does not happen.
That said, the DWP does not seem to have any patience and evidence has been ignored by a Decision Maker because it has been tardy. However, you have contacted them and a reasonable response would be for them to wait.
Sorry if this is not as much help as I would have liked.
Gordon