Thank you for the Chanukah wishes.
As for the spelling....
Hebrew, as a semetic language, has no vowels and when a word is transliterated into English there is a great deal of leeway as long as the sound is preserved. (There is a specific name for this but I won't bore you)
And yes, the "Ch" spelling is an attempt to be truer to the actual spelling/pronunciation of the word in Hebrew since it begins with the Hebrew letter Chet. This sound is not found in English and this leads to the confusion.
The letter CHET is equal to the number eight and is referred to as the letter of Life. (Chai = Life, L'Chaim = To life, etc...)
The number eight signifies the eight days of the festival of Chanukah (Festival of Lights).
The number eight also alludes to the eighth day of a Jewish baby boy’s life, when the ritual of circumcision (Brit Milah) takes place.
The word CHET also means ‘sin’ as well as ‘life’.
So all of the MANY spellings are correct. (Hanukkah, Chanukah, Chanukkah, or Chanuka) Hope this helped.