Otherwise, purchase the house and land by separate transactions.
^ Yes, that! Although you would presumably then need a residential mortgage AND a commercial one, unless you already have a pretty serious deposit?
Incidentally, when we bought our house with 5 acres and some outbuildings, we just got a standard residential mortgage and nothing special was said about that. However, in the legals, there was a line which said "the value of the house and outbuildings is taken as X, and the value of the fields is taken as Y". This means that if we ever sell, we would be liable for capital gains tax on the new value of "Y", if that makes sense, because it is not part of our primary dwelling.
Does that help?