Corps is available from the Charity Commission website: https://register-of-charities.charitycommission.gov.uk/
Just looked into this a bit more and there a guy on whatdotheyknow who clearly has some kind of bug-bare with West Mercia Wing, but looks like he might actually know what he taking about
I was happily reading through posts on this thread, thinking up replies as I went, then realised the posts were all from 2018!
As for getting copies of accounts. I would have thought you should also be able to get a copy from the chair/treasurer (if you can work out how to contact them)
not neccessarily the full accounts but CivCom minutes are found on SharePoint.
I know our Wing’s are available, as are all the Squadrons (which makes for interesting reading seeing how our neighbours are getting on).
Using that same format (site docs > admin > CivCom) route I have taken a look at the Regions.
One word: Shambles.
All except one (see below) have nothing before 2016, a couple have nothing, others from 2013.
Hats off to W&W though for having the most recent document, February 2019 with a sports and welfare fund – Sharepoint link