Can we or can't we make our own software to run in Windows 8 RT?

My company is thinking of upgrading our Windows to Windows 8 as well as adding new Windows 8 RT tablets for our users. We are hoping to use only Windows 8 RT tablets (as the users are asking for lighter weight tablets). We are currently using Visual Studio 2010 for our in house software development. I understand that we need to upgrade that to Visual Studio 2012 for the software to run in Windows 8. However, I read that all apps that are supposed to run in Windows RT must only be apps that is downloaded from Microsoft Apps Store. We DO NOT want to send our in-house software to Microsoft, as it is confidential to our own use only. Does this mean that we can't make our own software to run in Windows 8 RT of our own tablets?

I believe you will be able to develop your own RT apps and deploy them in-house, but your best bet would be to contact Microsoft directly.