Church conversions usually involve installing a mezzanine floor inside the main space to make it two floors as the ceilings are plenty high enough. Seen a few spectacular church conversions before but they take a hell of a lot of money and work, the end results can be breathtaking homes.
I've seen a couple of conversions and like you say, they can be spectacular homes. Friends did one in Mid-Wales, but the church was split into two properties.
Like Adzitude says, that is one big property for one family.