There is always some confusion regarding ‘tea tree’. Leptospermum is commonly called ‘tea tree’ and so are many Melaleuca species. Same family (Myrtaceae) but different genus.
The tea tree oil industry in Australia is based on Melaleuca alternifolia which are grown extensively in closely-spaced plantations mainly in the Northern Rivers region of NSW. There are three Melaleuca species (out of 200) that conform to the Australian standard for tea tree oil. M. alternifolia being the primary commercial choice.
Manuka oil is produced extensively in New Zealand by L. scoparium and has a range of therapeutic uses not dissimilar to Australian tea tree oil.
I do not think that growing Leptospermum to produce honey and at the same time produce foliage for steam distillation of oil is a very practical idea.
To begin with, both have entirely different cultivation requirements. If your growing Leptospermum in a plantation to maximise flowering, you will need wide spaced rows (5, 6 or 7m spacings) to optimise exposure to light. If your growing Leptospermum in a plantation for oil production you will need lots of soft foliage in low-grown plants on a very close spacing regime such as in the above picture.
Harvesting for oil will take place regularly, possibly once every 2 years or thereabouts and would require productive agricultural land and the extensive use of fertiliser and irrigation.
Extensive testing and analysis would also be required to determine the chemical composition of Australian Leptospermum oils.
Most importantly though is that Leptospermum produces flowers on last years wood meaning that if the foliage is being regularly harvested, then flowering will be severely compromised.