Bagpuss
regarding your query on salt licks etc, If you do want to feed a lick make sure that if sheep are likely to come into contact with it it is one designed for the sheep. Sheep are particulary intolerant of copper which all other ruminant species need and is usually contained in large amounts in mineral blocks, my day job is a as a ruminant nutritionist.
if you want my honest opinion on mineral deficiency in most lowland deer, I would say that any affect of drawing animals in will be solely related to the availability of salt. So rock salt would give the best affect.