The main medicinal use of lemon balm is relaxing and helps to overcome sleep problems. Use lemon balm as tea, or for a relaxing bath. In the kitchen lemon balm is nice in salads, sweet dishes and tea. You will not have to dry it because it will stay green over winter, even in Katoomba.
Lemon balm is a member of the mint family, but I find it to be far less weedy than mints. Honey bees like the flowers, however the herb looks much better if trimmed back. And as there are many uses this is an easy task.
Lemon balm is easy to grow and I find that some shade makes it look lush and green. Cut it back severely after flowering.
University of Maryland
East West School (includes how lemon balm is used in Chinese Medicine)
The Guardian (with a lemon balm wine recipe)