From registry office to Catholic Church wedding

Regarding the venue change, just talk to him about it. "Fiance, I've been thinking about our wedding, and I'd really like to have a church ceremony after all - how would you feel about that?" If he feels uncomfortable with having a religious ceremony when he is non-religious, then I think you need to respect that. You should also check with your priest to make sure he is happy to officiate at a wedding where one partner is non-religious - some will be and some won't.

The church costs seem high - is this a church you attend regularly? I know that with many Anglican churches, they charge high rates for people who are not church-goers, but just want a 'pretty church' for the photos, but tend to charge much less for those who are actually part of the church. So if you are a regular attender, it might be worth asking what the costs would be for you. I had friends who got married in their local Anglican church (where they were active members) and it cost them a fraction of what it would have been if they had just been picking it as a 'wedding venue'.