Cluster Sampling and Standard Errors

I looked around to find the answer on this site but did not find any, so I apologize if this has been discusses recently and would welcome redirection.

My question deal with descriptive and inferential statistics and Cluster Samples. I was given 6 data sets which I got statistics for but my question is - how do I calculate the standard error for the overall sample? Secondly how do I calculate a 95% confidence interval for it? Below is the key information I calculated of the data set (the image). (p.s. there are a total of 45 clusters). I also attached my excel sheet with all the calculations with my best guess of how to do the 95% confidence interval.