Combine the dry ingredients in a bowl and lightly whisk together.
In a separate bowl, combine the wet ingredients (including the zucchini) and lightly whisk.
Make a small well in the centre of the dry ingredients and pour in the wet ingredients. Mix together with a large spoon or the kneading attachment of a kitchen stand mixer until the dough comes together. DO NOT add in the blueberries yet.
Knead the dough for 3-5 minutes on a well greased surface using the additional arrowroot. The dough will be sticky and not behave like normal dough. Use additional arrowroot to prevent the dough from sticking and incorporate it into the dough.
Place the dough into a greased bowl and cover with plastic wrap or a damp tea towel. Place in a warm place to prove for 1 1/2 hours. If the wether is warm find a place free from the wind, or if it is average use your car boot. If desperate, preheat the oven to 70C, then turn off the oven and place the bowl inside leaving the door ajar.
Preheat the oven to 200C/400F. Line and grease a baking tray.
Gently fold in the blueberries into the dough.
Divide the dough into 8 equal balls (give them a squeeze to compress the dough together) and place, close together, on the baking tray.
Place the tray in a warm place (the same as before) for 30 minutes. If you used the oven for the initial rising then do not preheat the oven until the 2nd rising stage is complete.
After 30 minutes, make the cross plaste and place into a zip lock bag and make a small cut at 1 corner. Make crosses over each bun.
Bake in the hot oven for 25 to 30 minutes and remove. The buns will be slightly brown on top and have a firm bottom.
With 5 minutes left of baking, make the lemon glaze (see below) and immediately baste the hot cross buns with the glaze when removed from the oven.
The hot cross buns taste best warm, and can be reheated once cooled. Keep in an airtight container for up to 3 days. They can also be freezed.