Does anyone know how to serve my own files like TestFlight or Diawi ?
I used Firefox web developer tools to let me pick up the header information (from Diawi) then used PHP to set header and readfile to output but this has failed - I have also tried to just reference the file via my web browser but each time my iPad Safari tells me it cannot download this file.
Don't try to download .ipa file directly, you should create manifest.plist file that contains app information and create a link to this .plist file like below. Than go to this link via safari.
Manifest file should like this : https://gist.github.com/hramos/774468
And you link should like this:
itms-services://?action=download-manifest& url=http://example.com/manifest.plist
You can check this page: Wireless AdHoc Distribution