Are most oats grown not Spring oats? If so that's probably what you will get if you buy unnamed seed. I don't know if it matters and I guess planting 1kg would be a way to find out.
What do you plan to do with the oats SallyintNorth? I just ask as processing (particularly dehulling) oats is much much more difficult than wheat or rye, to the point that modern small-scale processing is nearly impossible.
I grew some spring oats this year and, when I get time this winter, am going to try and get them into an edible state.............