I can only speak from my personal learning experience(s) as an adult, which admittedly is very different from learning in school, as one has to be self-motivated and proactive.
Firstly with learning foreign languages: if I was struggling with a particular concept, I would find as many relevant online resources as I could, and pick out the bits that either gave me extra practice to reinforce the concept, or that helped me to understand it better.
Currently, I have just started teaching myself to play the piano. I am using a book aimed at adult learners, and it is turning out to be a great book, but as with languages, if I am unsure of something, I am turning to the Internet. YouTube is great as there are so many videos that can quickly clarify things.
Even if I had a tutor, I am sure I would still use all these extra resources too.
HMRC slightly angry is an understatement
