I know many people who became hozer be teshuva and they’ve asked the Gavad Weiss where to learn, and he’s suggested the Litvish BT yeshivos, like Ohr Somayach.
If I were to pursue this course of action, I’d take college Hebrew for 2 years, go to Ohr Somayach for 5-6 years, and then go to Marbeh Torah.