The tradition that both Ajahn Nitho and Ajahn Brahm are connected to comes from Thailand, and it was Ajahn Chah and his successor Ajahn Liem who were the teachers and mentors for many of the Western monks.
Ajahn Ganha is a nephew of Ajahn Chah. Some of his teachings have been translated to English:
Ajahn Chah was an important factor when Theravada Buddhism spread to the West, because many Westerners took an ordination with him. A lot of his teachings have been translated to English, and can be bought on Amazon. The two biggest collections of teachings in English are for free distribution: