Tread Carefully
***disclaimer not current in HM tax knowledge***
You can (could) claim the difference between your mileage rate and the official HMRC mileage rate as tax relief for official duty journeys. This is not an HM forces thing..it applies to very working person in the UK.
Home to Duty does not (did not!) count. Your journey to and from your place of work (whoever you are in the UK) cannot (should not) be used to claim this tax relief. Nor should things the RAF consider "duty" (sports, medical trips) but HMRC does not consider "duty".
That does no mean you can't submit these excluded journeys, get them paid, and never hear about them again.
However, if you are one of the random percent that get audited (within six years) welcome to a nauseating amount of paperwork trying to untangle the "duty" from the "HMRC-don't-count-that-as-duty-whatever- your-SHQ-says".
Been there, done that.
More than happy to be corrected on any of the above...anyway, if you are in any doubt, get you guidance from HMRC, not SHQ!
Edited to add to the post above..."normal place of residence to normal place of work" is what we call home to duty and everybody else calls the daily commute. So yes, the example in the post above probably is OK.
Same advice, if in doubt, check with HMRC.