You can take whatever university degree. Read list of mandatory subjects. Take sylabus and list of recommended literature for every subject. From list of resources take one or two and read them. Almost every course has some fundamentals and introduction to X, to get all students on the same starting line. What you will not understand just ask someone more experienced or google it. Experienced colleague* he wil tell you some hidden notes or let you know this is not so important for your future career if dont wanna be xyz. Take just one and intensive course for month.
We are not fulltime students so we dont have such amount of time dedicated for study.
*you need to have trustworthy colleague who will support you. I know some highy skilled professionals but communication and learning from them is very difficult.