I have recently completed a course in Management delivered by the which is a four month part time course covering eight modules.
It may not be as specialist as you may require, but it offers a good grounding in current law and personnel management that a good business manager would require.
It also covers the kind of investigate work you should engage in when assessing a business as a prospective purchaser or investor, based on published figures from them.
This is not a "quick fix" and I must say that while I have good experience in helping to run a practice and running my own sole tradership, it was a steep enough learning curve.
Thus you must be prepared to step back from the level of expertise you have attained as a professional and become a student at a different discipline, business, from the ground up.
Its not an easy thing for any mature student and a mature professional may find it even more difficult, but the rewards are partly the knowledge of subjects and partly the self-knowledge.
I have no connection to BMI other than having done this course and I highly recommend it as an ongoing CPD exercise, because its all too easy to be left behind in these days of increased standards.
ONQ.