Preheat the oven to 180C/355F. Spray two baking trays with oil and line with baking paper.
Melt the butter either in a large saucepan on the stovetop, or in a big bowl in the microwave.
Add the golden syrup, honey, water and baking soda and stir.
Stir in the oats, flour(s), coconut and sugar until you have a dough that's sticky but not runny. Add more oats/flour or water if necessary to get the right consistency.
Use a small ice cream scoop, metal spoon or just your wet hands to make small balls of dough. Place on the baking trays with at least 2 inches between each ball (about 8 or 9 on each tray). Flatten down with damp hands or a fork (flatter biscuits will tend to be crunchier).
Bake for 12 to 18 minutes, depending on whether you prefer chewier or crunchier biscuits. The biscuits should be light to dark golden brown, but not burnt of course.
Let cool on the baking trays for 10 minutes. Then transfer to a cooling rack and let cool completely before storing for up to 10 days in an airtight biscuit tin or sealed container. The biscuits may get softer as the days go by. To crisp up again, heat in the oven for 5 minutes at 180C/355F.
