I am a secularist, but I can see that this is not straight-forward in a country with an established church, and one which holds huge assets in trust for it's parishioners (which to a certain extent includes everyone not just believers).
Much as I would like to see religious influence privatised, I don't think CoE assets (which includes churches and schools but also loads of farmland, housing and commercial buildings operated as a landlord) can just be privatised to believers.
For example, if the Catholic Church or a sect of Judaism found that it no longer had enough congregants in a particular area I think it would be fair enough for them to close up, sell the buildings and invest their money in assets to serve their congregants elsewhere (evening that means in Israel, Ireland or Rome or wherever). These religions are like private clubs, they can what they like with their own assets. I don't think the CoE can or should do that (e.g. Selling up and transferring assets to Anglicans in Nigeria say).
I am not sure how you solve that so that the church can fulfil it's legitimate role as a club for adherents, without privatising assets that
were meant for the benefit of the people of the country?
The trouble is it can be too much of a temptation for a club that is losing members to use it's assets to retain an unbalanced share of power and influence (...as with school admission rules used to get bums on seats in church..). This relates to Holo's point about "who will run the youth clubs" etc... But holding people to ransome by sitting on national assets is not exactly the moral high ground.