Christian celebrant

I suppose you could do an internet search, but I'm not sure how likely you'll be to find one. Most people who have a registry office wedding (I'm assuming you are doing the legal bit at a registry, since you can't have religious elements in a legal civil ceremony) but want some Christian input tend to have their minister do some kind of blessing afterwards, so I'm not sure there'd be a huge call for Christian wedding celebrants.

(Of course, that is the alternative - that you ask a minister or even just a friend who has a Christian faith to do a reading or blessing)

I think there must be lots of celebrants with a Christian faith who would love to officiate at a wedding with a little more leaning to their faith. I don't see the problem in asking ones that you like the sound of the actual question. Tell them about your faith and ask them if they could could perform the ceremony in that way.

I have shot plenty of weddings where they have had a civil wedding followed directly by a blessing but it has always been at a venue that has an attached Chappel or Church which usually means a large country house stately home kind of a venue.