Hiding letter frequencies with Huffman codes

To hide letter frequencies, one can Huffman code. Is there a standard Huffman code for English? A tree can be encoded in preorder. To hide double-letter frequencies, one can have a Huffman code for each letter predicting what the subsequent letter will be. Is there such a standard code? Next, bits can be grouped by (say) 5, and the key, one of the (2^5)! permutations is applied as a substitution cipher. How would one crack such encryption?