1) Using a vegetable peeler remove the zest of the oranges and lemons. Cut the zest pieces into thin slices, then finely chop or grind and set aside. Peel and discard remaining white part of the peel from fruit. Chop fruit pulp, reserving any juice and set aside.
2) Place the peels, water and bicarbonate of soda in a saucepan. Bring to a boil over high heat. Reduce the heat, cover and simmer for 20 mins, stirring occasionally. Add the reserved fruit and juice and cover. Simmer an additional 10 mins.
3) Stir 1.2kg sugar into the prepared fruit in the saucepan. Add the butter to reduce foaming. Bring mixture to a full rolling boil on high heat stirring constantly.
4) Stir in pectin. Return to a boil and boil exactly 1 min, stirring constantly. Remove from heat and skim off any foam with metal spoon.
5) Toss the blueberries with honey. Place into a small saucepan and cook over medium heat for 1 min. Scoop out blueberries and add to marmalade. Reduce liquid to a syrup and stir into the finished marmalade. Serve at room temperature.
For the biscuits:
1) Preheat oven to 220C/Gas 8.
2) Combine flour, baking powder, bicarbonate of soda and salt in a large bowl. Using a dough cutter, combine until ingredients are incorporated. Scatter the cold butter pieces over the top of the flour mixture and continue to combine until the mixture resembles coarse meal. Add the buttermilk and pulse until the mixture just begins to come together.
3) Scrape the dough onto a lightly floured counter. Pat the dough into a 25 by 30cm rectangle about 2cm thick. Use a 6cm round cutter to cut out biscuits. Press together the scraps of dough, and repeat process. Place the biscuits on 2 baking tins lined with parchment paper; brush the tops with cream and sprinkle with black pepper.
4) Bake the biscuits for 12 to 15 mins or until lightly golden brown. Remove from the oven and brush the tops with melted butter.