I am looking for some advice here. We live in a ground floor flat in a converted Victorian semi, we may be in a position to pay off our mortgage early using savings, and then potentially buy the top flat with a mortgage whilst renting the ground floor via airbnb or something to cover the mortgage cost, and then convert the two flats to one house later down the line if worth doing, but I wouldn't mind keeping the two flats separate either.
Good idea?