I attended a briefing by NASA a few years ago in which this was discussed. The location of choice for a minor but significant problem during launch is Sigonella, Italy, although there are several others within Europe that could be called upon. They went on to suggest that if such an event happened, the Shuttle would immediately claim the Blue Riband for the fastest Atlantic crossing in the certainty that they would keep it until time immortal. I had heard a rumour of Manston being the UK airfield of choice because of its width and length but have no reason to not believe that Fairford would be an alternative.