Terms And Conditions Question

I would ask if you could see a copy of the terms and conditions before you pay a deposit. What if there is something in there that's a deal breaker for you but you've already given them a deposit.

I would not pay a deposit without having seen the contract first. They should provide a copy of the contract for you to review pre deposit, you need to ask them to do this so you can check it before parting with any money. Also, make sure you have booked the registrar for your date and time before you secure the venue, of the registrar is not available then you won't be able to legally marry on the day at the venue
Most registrar's will let you pay a holding deposit to secure the date and then you can book the venue