There is a chain of shops in Oz called "The British Lolly Shop" they dont just sell lollies though ..LOL!..thats what the ozzies call sweets ...lollies ...(strange people!)
they sell loads of different cadburys choccy bars ... so tell your wife not to panic! .. I was the same about choccy buttons ... but now that I KNOW whee to get them from i am happy to move to the land downunder!
There are also many websites in oz where you can order british foodstuffs.