I too have a family member who escaped from the drudgery of manual labour, this time in the coal mines, by persuing a career in music. William Thompson, son of a pit sinker turned violin maker, went from a job as a Colliery Time keeper to beating time in the theatre orchestra, first at Bishop Auckland 1891 and then in Leeds 1901. I doubt he studied conducting or how to lead an orchestra in a conservatoire! There was a strong folk music tradition amongst the miners, and the violin was a popular folk instrument.
I suspect quite a few people in the 19th century setting themselves up as music teachers or "professors " did not have any formal qualifications as such.