I would imagine it's just the chancel because that's the most important bit of the church, as it contains the altar (or high altar).

It might not be in the church's interest to ask you to pay for repairs; I have a vague idea that that would jeopardise their chances of getting funding from some bodies - English Heritage, or the Heritage Lottery Fund, or both.

Anyone can baptise in an emergency as well, so there would be nothing to stop you doing that if you felt so inclined. In fact you could probably do a lot of things that a priest/minister does; not weddings, of course (or not legally), and I'm not sure about funerals. But no one would stop you preaching or visiting the sick ...