If they put Harry Potter on the reading list, it will be the most oversubscribed course in the school.
I’ve got no problem with this at all - Britain has been pagan a lot longer than it has so far been christian.
As long as children are taught about it objectively as the belief system that christianity replaced, then knowledge is a good thing.
I teach a Harry Potter lit class and it is quite popular. I also teach to my Brit lit students Druids, paganism, animism, ect. These topics have a major role in early British literature.