The Oak is the section of the Temple dedicated to Druidism and Celtic Paganism in their various forms. Druidism is the most immediately recognizable part of this section, as it is the most readily recognized aspect of Celtic Pagan beliefs that has remained with us through the ages. Less recognized is Celtic Reconstructionist Paganism, which seeks to recreate a version of classical Celtic beliefs in the modern world. The latter often gets less attention, as many of its gods and goddesses have been co-opted by the heavily Celtic influenced Wiccan traditions that exist in both the Americas and in the UK.
Druidism has a long and interesting history, with much of the classical documentation of it coming from Roman observations and writings. Monolith builders and an integral part of the early Briton social and cultural systems. It also had influence on the continent, although it was in competition there with the religious beliefs of the Franks and early Germanic peoples. Modern practices began to crop up during the romantic period of the 19th century, and by the Pagan renaissance that began in the 1960s and 1970s, it stepped back into the limelight in a serious way. Druidism has large numbers of followers in Canada, the USA, and especially in the UK. It also has a number of robust, organized bodies that work hard for full governmental recognition of Druidism as a religion.
Celtic Reconstructionist religion is a robust but small group right now, who exist in competition with Neo-Pagan and Wiccan organizations who have largely coopted their gods, goddesses, terminology, and holidays. They are however, an active and educated group, as are most Pagans on the path of reconstruction. As with Druidism, Celtic Reconstructionist Paganism can have very strong connections to the culture of the Britons, and UK in antiquity, but has some roots on the continent as well.
Where Wiccans have Covens, and Heathens have Kindreds, Druids and Celtic Reconstructionists have Groves. Trees and nature are a very important part of the Druid and Celtic Reconstructionist worldview and ideology. Worship typically occurs out of doors, in all weather, and depending on the ritual or celebration occurring, at all times of the day or night. Ritual formats are available from a number of sources, but those of the Ár nDraíocht Féin (ADF) are the most common.
There is currently no Grove in the Okanagan Valley, but there is an effort occurring to start one.