Yes, best to check here before calling!

You can rebook from a cancellation for -3 days to +14 days on any flight with space in the cabin. Because of your mangled booking, the rebooking screen may not work too well now, but give the agent your preferred flight and they will do so. The -3 to +14 days is the standard offer, you can actually rebook to completely different dates via Buy with Confidence if you wish. And you can fly to Edinburgh as an alternative too.

Consider Following BA on Twitter and then sending a Direct Message to speed things up with the rebooking. Because it's a redemption booking, unfortunately you can't call Barcelona or Prague tomorrow, these calls go to Bremen but they can only handle commercial bookings.