When you talk about breakfast oatmeal you may mean something like Quaker porage oats (note the real stuff is spelled porridge!) - this won't do.... they are processed oats and will not give you the correct texture of proper Scots steel cut oats. They are not suitable for things like traditional Scots oatcakes or even cranachan.
I only use oats products from Alford Mill. Here's their website - but I don't know whether their products are available outside Scotland.