I don't think blackthorn is good for stock and it's invasive and leaves long scratches on your arms which can take months to heal. Mirabelle would be better - same early blossom, some thorns, useable fruit, totally hardy, and can become either a sturdy tree or be kept cut as a hedge.
Most of our hedges are mixed, with an outer row of hawthorn to provide a dense and eventually stockproof barrier, and can be laid when large enough. The inner row (hedges are best planted in double, staggered rows) to include holly (evergreen), bird cherry, hazel, rowan, hornbeam esp if your ground is wet, oak, Scots pine as occasional standards along the row, beech which holds onto its leaves a bit so gives some winter cover, field maple, spindle. Balm of Gillead gives a beautiful scent which carries on the wind esp before the leaves come out - keep it trimmed though because it can become a tall tree - it's perfectly hardy. I add some roses at intervals, dog rose and the Scottish rose which is a pale yellow with black hips (I think that's the one
). We also have included hawthorn in the inner side of the row. I avoid elder as although it has lovely flowers and useful berries, it takes up a lot of space but is short-lived, so leaves a gap after about 15 years. We have several elders around, but not in the hedge. We also have ash in the hedge, but because of the die-back disease it's probably best to avoid it at the moment. I really enjoyed planning the species we used in the hedges, and the proportions. Best planted in winter obviously.
For your willow hedge, perhaps you could plant an edible one about a metre away; it grows more slowly than willow and would be protected from the wind by it. We found it difficult to establish anything on our west-facing march because of the howling wind, but it seems to be happier now. Once that bit grew and was established, you could pollard your willows at hedge-top height and include them as a top layer. I would use goat willow or similar as it grows quickly but is sturdy, unlike crack willow which does just what its name says
. The fields of willow you see are for biomass to feed boilers and power stations.