As well as Morrison's, Waitrose has expressed a commitment to retain fresh fish counters in its supermarkets. Have you got a (larger) Waitrose near to you, Barry?
Upmarket 'food halls' often include a fishmonger's counter within them. That might be on a daily basis or just on a weekly 'pop up' one. (e.g. Suffolk Food Hall, near to me, has a pop-up fishmonger's stall every Thursday). Perhaps there might be something similar in your area? (If you'll tell us roughly where you live, I'll see if I can find anywhere that you might have missed).