The UK has a notion of "Listed Buildings". These are buildings that are recognised as part of the national heritage. Generally, listed buildings can't be modified or destroyed. Any building may be listed, but many mosques, temples, synagogues, and particularly churches are listed, as they are old and culturally significant.
Listing a building places expectations on the building's owner. The owner can't develop the building. Thus listing reduces the value of a building. There can be a temptation to allow a listed building to fall into disrepair, so its listing is removed and it can be sold profitably. This is counter to the intention of listing, which is to preserve.
The government offers financial support to owners of listed places of worship. It takes the form of grants which relieve the owner of the sales tax (VAT) on the cost of repair. Note that many other owners of listed buildings (such as schools or businesses) would be able to reclaim the VAT as a business cost from HMRC.
It seems to be a fairly transparent scheme. The amount of money available is capped by its budget at £42 million, and there are listings of the amount paid. In December 2021 £2,657,970.11 was paid under the scheme.
You can visit the scheme's website http://www.lpwscheme.org.uk/index-3.html (it's clear that they haven't spent lots of money on a webdesigner)
Far more money is spent on education. Many schools are linked to churches. But again, this money has a specific purpose and has to be spent on teachers, as these "voluntary aided schools" provide free education. The budget of the school is quite separate from that of the parish.