I do not know any spanish school in north part of Bogota. Last year I was taking course in Spanish World Institute, which is located in Chapiniero. It is possible to reach the school from North part by taxi in around 40 minutes (I lived in Santa Barbara), depending on traffic conditions.
You might want to look for alternative spanish schools, I think one is located in Candaleria and another in Sabatena campus outside Bogota.
I believe you can get a student visa after you arrive and start studying at a school. I have read of a few people doing this-entering with a 60 day stamp in your passport and then having a language school certify you are enrolled for study. With that proof of enrollment DAS can issue some short of student visa. I'd either check with a Colombian Consulate here in the US or call some language schools in Colombia.
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