I live and work in the UK and in Germany. My first Apple ID is registered and linked to App Sore UK. I can't shop in the German App Store with that, but the App I need is not available in the UK store. I have set up a second Apple ID with a German email address, but how can I add this to my iPad so that I can shop in the German App Store?
Go to Settings-> iTunes & App Store then tap your UK Apple ID and tap "Log Out". Then just sign in with your German Apple ID. After you've downloaded the app, you should be able to switch back to the UK Apple ID in the same way without anything being affected.