Put the caster sugar in a food processor and blend for 5 minutes until you have a fine powder. Add the citric acid and bicarbonate of soda and blend again until thoroughly combined. Tip half the mixture into a bowl, reserving half for later.
With the motor running, add the lemon extract and the pink food colouring to the remaining sherbet. Transfer to a bowl and set aside.
Transfer the reserved half of the sherbet to the food processor and repeat step 2 but with the orange extract and red food colouring. Layer the two types of sherbet in a glass jar and seal. It will keep for a month in a cupboard.
Place a piece of baking parchment on a baking tray and draw 6 circles with a diameter of 4½cm. Turn the paper over so the circles are underneath.
Combine the granulated sugar and golden syrup in a small, heavy-based saucepan. Add the cream of tartar and 100ml water, then set over a medium heat to dissolve the sugar, stirring often.
Once the sugar has dissolved, place a sugar thermometer into the pan and bring the syrup to a boil. Continue to heat over a medium heat until the syrup reaches 155°C. Remove the pan from the heat and add the lemon extract and a few drops of red food colouring, stirring until the sugar syrup is red. Leave for 3-4 minutes or until the syrup has thickened and cooled slightly.
Working quickly as the syrup will start to harden, use a spoon to carefully create circles on the baking parchment, using the circles drawn on as a guide. Press the sticks into the centre of the lollies and sprinkle with the sugar decorations. Leave to set.