I dont know if this has come up before, but ive had an idea for another ancient religion which would more or less, require no work as it could use all the TOG norse stuff.
Anglo-Saxon Paganism. Wodanism?
It would be triggered by a smart [good traits or high learning] Saxon or English culture, Norse Pagan (reformed or unreformed) religion character being an independent ruler [duchy or higher] in de jure England taking a decision to reclaim England from the Norsemen without resorting to christianity.
Representing a liberational movement in a norse dominated england, with the converted to paganism by their viking overlords english/saxon nobility throwing off the nordic yoke without abandoning their new found paganism by 'reviving' the faith of their fore-fathers.
Possibly the decision would have some name along the lines of Reclaim the Legacy of Wodan.
Maybe they'd get claims of all norse culture held titles in de jure england along with it?
Maybe with the religion as a 'heresy' of Reformed Norse Paganism [by event if it exists at the time of schism], and probably starting off Reformed to represent it being created politically, organised to support the reclaimation of england.
And mechanic/event wise it could just use all Norse' stuff but with Odin changed to Wodin and etc references to nordic locations/history changed to english stuff.
It works as a plausible religion to survive as A. It died within the living memory of very old people at the start of the game,
B. Aside from Fairies, Elves and Dragons being more important, its basically the same as the Norse religion which is flooding into England at the start of the game,
C. In the context of Norse Pagan English rulers finding themselves an identity distinct from their conquerors and a divine right that supports them and denounces the overlords, it makes sense.