Absolute legend! Honestly having scoured the web thought it was game over and that I would have to start from scratch on a number of games. This worked seamlessly!
Update - fixed the problem. Down to using a mac...
So I was running an older version of atmosphere FW 9.x. Updated atmosphere and used daybreak to update to 13.0. Now after launching CFW get to the Nintendo logo and then it reboots to hekate. Any ideas?