The Community Ownership Fund was set up to help communities across the UK take ownership of buildings and assets at risk of being lost. It is most relevant to churches that are being transferred from denominational ownership to community trusts, or that already operate as community-run venues.
For a standard church still managed by its denomination, this fund is unlikely to be the right fit. But for a redundant or closing church being taken on by a community group, or a church that has already become a community trust, it could provide substantial capital for renovation, including heating. The match-funding requirement of at least 50% is a significant hurdle, so you will need other grants or fundraising in place.
Note: the Community Ownership Fund ran in bidding rounds through 2022 to 2025. At the time of writing it is not clear whether further rounds will open or whether a successor programme will replace it. Check GOV.UK for the latest position before investing time in an application.