As my friend gardening in Thurso has discovered, if you first establish yourself a good windbreak, then what you can grow greatly increases in variety. Your beech hedge may be good for that. Sitka spruce is a very good windbreak. There are also several kinds of willow which make good windproof hedging, I can't remember the precise type, but there is one particular one with pale coloured, broad leaves which is commonly used in Iceland for hedging to establish a windbreak, (maybe Salix lanata or S. lapponum or S. aurita or something) behind which you can grow your redcurrants, spiraea, potatoes, rhubarb, and whatever else Icelanders like to grow. If you are in a milder location somewhere not too far from the coast, even up a hill, then probably what you can grow behind that windbreak is much greater in variety than if you are inland and prone to nasty winter freezes and cold dry winds.

If you go to southern patagonia, a very windy place, you will observe that the shrubs there tend to be cushion shaped. I'm not entirely sure what the various "spiny cushion plants" one had to avoid sitting on were, but they were quite various, and survived remarkably terrible conditions, in effect a range of different gorse-like plants. One non-spiny patagonian cushion-like shrub I do know you can get here from specialists here is Baccharis patagonica, though if you are inland in the grampians it probably won't be hardy enough for you. Quite a few berberis will probably do you too, many of those are from Chile.

The dominant tree in Patagonia is Nothofagus antarctica, which bonsais itself rather splendidly in an exposed location, though can't grow in the most exposed locations. I have a N antarctica in my Bucks garden, and it is quite fast growing, after 7 yrs it has now equalled in height the 20-yr old scots pine and picea glauca in the garden. By having very small leaves and a sparse larch-like branch structure, it shed wind easily. It grows slower in windier places. A lovely tree. Nothofagus betuloides is a another wind-resistant tree from southern Chile, an evergreen this time, but it prefers damp wind to dry, so probably won't do in the Grampians. Actually does better in a windy location, because otherwise it grows too fast and then gets knocked over when it is windy. If you read spanish, you may find further interesting ideas here. http://www.florachilena.cl/

I expect there are probably bamboos you can grow. They are shallow rooted, many are very hardy, and some of them really do very well in cool damp summers. Doesn't even have to be too damp, Phyllostachys aureosulcata does well on the East coast of Scotland. If a taller one such as a Phyllostachys really won't take your wind, then there are shorter low growing ones. Bamboo specialists will advise.