The setup in most places is to have a single temple primarily for Dana and Lugh with lesser shrines to the other deities. The priest of The Circle in residence typically follows Lugh or Dana as their primary, but could a cleric/druid of any one of the others.
In Ceirin there are two temples one for Dana and one for Lugh, each with the lesser shrines for the other deities. The party has primarily dealt with the priest Gllucan in the temple of Lugh. The other temple and priestess of Dana is considered the primary temple for the territory.
The Sanctuary of Arawn is quite some distance to the east and south, close to the border of Haradan (where Nefer is from)... If you look at the continent map, its in the middle/southern portion of the Arandil Forest.
The Sanctuary of Arawn is like the Sun Temple in that it is built around one of the great stone circles of the Ancients and has one of the Great Trees of Angtiria (The Tree of Ross). While the Sun Temple is known for its Foundry Stones (clean energy) among other things, the Sanctuary of Arawn is known for being able to summon the Wild Hunt (to protect or punish as determined by The Circle and Arawn). The Sanctuary and the Clans in that territory are the primary guard against incursions from Haradan (usually for lumber and slaves).
Your character can address his spiritual needs with any priest of the Circle, but I will say that at the temple of Dana there is another priestess specifically of Arawn, who is a member of one of the Clan Fionn families, but who is frequently out and about the clan territory (if it becomes important I will work out more details).
Although the actual battle was anti-climatic, the Owlbear is a fearsome foe and also an "abomination" something not part of the natural order that should generally be killed, so that is a very appropriate/impressive sacrifice.