GKK Health Insurance in Austria - How does it work for the self-employed

In the next year or two my husband and myself intend to move from the UK to Austria and hopefully buy and run a small guesthouse or apartment house in Carinthia or Styria. So far we have found information about the GKK health insurance which relates to those working for an employer but we are finding it difficult to obtain information for the self-employed. Any info about how we would apply and any estimates about how much it would cost us would be gratefully received.