"Do supermarkets carry this "cracked or steel-cut" oats or do you have to get it from the health food store usually?"
I get mine from Canada's Bulk Barn chain - it's labelled there as "Scotch oats". It's easy to spot - just look for small bits rather than rolled. But, Quaker's 'old fashioned' rolled should be almost as good - I used a lot of it for my children's favourite oatmeal cookies.