This recipe sounds good. The cream would only make it richer, but katiekeeva is right! Water will do and it will still taste great! By the way, Half and Half is also known as "Cream-o" and has 10% milk fat. Coffee cream is 18% milk fat. But if you used half cream and half milk, what kind of cream would you use? Whipping cream can be around 35% milk fat; sometimes it's more, if it's specified as heavy cream. So half skim milk and half whipping cream would make it more like coffee cream than Half and Half.