Hello Patrickjnrhill,Â
Welcome to the Apple Support Communities! From your message we understand that you are unable to download any apps from the App Store as it's seeing your Apple ID is associated with the US store.Â
You are correct when you say that you would need to spend any store credit remaining on your Apple ID. This article provides you with all the details: Change your Apple ID country or region. If you find you have any questions or need further assistance, you'll need to follow the steps under "Contact Apple Support," in the same article.
All the best.