Chocolate Royals are a brand of chocolate covered marshmallow biscuits made by Arnotts in Australia. You can also buy a similar version from Aldi called Clouds.
You can buy lolly spearmint leaves from the confectionary aisle of most supermarkets, Big W or Kmart etc (I bought the Black & Gold brand from IGA).
If you can't find spearmint leaves, you can use a couple of green M&Ms in their place.
Jaffas are red covered chocolate balls that you can buy from most supermarkets. If you can't buy Jaffas, you can replace them with red M&Ms.
I like to add melted chocolate to 3-4 biscuits at a time and add the spearmint leaves/jaffas immediately before the chocolate sets. Repeat in batches of 3-4 until all of the biscuits have been decorated.