I understand you now better. Dragon can also say RYU 竜. I think RYUU is better in this case, speaking about Martical Arts. TATSU is mainly used to say about chinese horoscope as Dragon.
As you say SCHOOL is 学校 GAKKOU but in your case you are not talking about elementary school, Junior high school, High school... and the word Acadeny isn't usually used to say about Martial Arts. So Japanese Translation in this case, in my opinion, DOJO may be more suitable.
anyway everyone can understand the meaning even if you say Gakkoo 学校
Nice to know you are going to re-study Hiragana and Katakana writings
I think this list can help you to practice again. I am uploading these videos i hiragana ato first but I wil continue with Katakana just afer HIragana