It isn't exactly a platform, but it sounds like you would be well served by The Theoretical Minimum [0]. The courses [1] start at classical mechanics, but the second one is QM and builds from there. They are all taught by Leonard Susskind, who is a fairly big name in the field.

There are two books available specifically tied to The Theoretical Minimum [2], but I'm not sure how they related or tie into the video lectures as I have not read them myself.

[0] http://theoreticalminimum.com

[1] http://theoreticalminimum.com/courses

[2] http://theoreticalminimum.com/references