what would be a good white offense and gold defence?
First of all, welcome to the boards! You appear to be from MN - I might know you from tournaments if you ever come to the Twin Cities area.
Second of all, in answer to your question, The Garden Tomb is the most popular theme to use with white. However, that isn't typically paired with a single-brigade defense, so Musicians would be the next best choice. And Egyptians is really the only viable exclusively gold defense, as Herods are a just-starting theme and don't usually do well in single-brigade. (You could combine the two gold themes if you wanted, however.)