American iPad in the UK

Possibly. Take it to a local Apple Retail Store Genius Bar and inquire. http://www.apple.com/retail/geniusbar/

"Apple may restrict service to the original country of purchase. If your iPad requires service, you can contact Apple Technical Support or take your iPad to your local Apple Retail Store or Apple Authorized Service Provider, where available, for diagnosis." http://www.apple.com/support/ipad/service/faq/#repair3

I asked at the Apple store here in the UK if I bought an iPad in the US, would the warranty be valid here and I was told "Yes".