Since they operate several days of the week I would presume there's a change of crew. I would imagine that the routing would be via the southern tip of Iceland and Greenland, so sufficient options. Don't know what you mean re WX diversions at the Scottish end. Plenty of airports in Scotland and there's always Belfast too. It would be a standard configuration and well within range limits.
Average flight time eastbound is 4hrs and 50 mins. Westbound 6 hrs.