First of all, thank you to all of you who gave me tips, advice and support last week when Murphy came to join us!
I've taken everything on board and am pleased to say that you were all completely right when you said that the issues with the cat and the sheep would calm down.
Murphy follows me about while I do my jobs in the garden/fields now and is great company. First week kept him on his lead, now he just follows me and if he gets caught up sniffing I call him (in that silly excited voice

) and he runs over and is rewarded.
Walked in the sheep field today, the bossy ewes kept an interested eye on him but no attacks.
We start training on a good citizen scheme on January 5th.
Occasional poo accident in the house still, working on that though.