To make invert #1 sugar, combine 2 parts sugar and 1 part water (eg. 670g sugar and 330ml water) and heat to 100 °C for 15 mins. Then add c. 1/4 tspn citric acid and heat to 114°C for 5 mins. Allow to cool before transferring to jars. to make Invert Sugar #2, bake in an air fryer on the "Bake" setting, if you have one, at 150°C for 1 hour. Alternatively, use pale Invert Syrup (available on Amazon) and bake for the same duration. If neither option is feasible, substitute with dextrose brewing sugar, or golden syrup and possibly add a few millilitres of Colour Carmel (E150c or d) if that's convenient. Check the baking section of your supermarket or buy a little Murphy & Sons Carmel colour if you plan to make a lot.