Hi Alice! What kind of work are you looking for? Because you can work in different "horsey" places like stables, tack shops or companies related to equestrianism!
The first place came up to my mind when I saw your question was Bates Saddles! They are Australian and maybe they are lookingto hire new employees!
Hope it helps! 😍
Maybe ask around with local professionals and see if they are open to taking you for week? Not sure where in Australia you are located or what discipline you are interested in, but you could always try the local racecourse trainers or any horse breeders around your area that would be able to take on a work experience students