The engineer I spoke to said he thinks it's more likely leaking from the core plug from the pictures as he can't see the crack going in far enough to reach the water jacket.
Once I get the car back and take the head off it will be dropped off with the engineer who said they will pressure test it and said they will replace the core plug and weld the flange up and then machine it back to the correct shape and level. He said it's an easy fix but just a shame it's got to be removed to do it.