I've been playing guitar for a while now, self taught but i feel like I've not been improving.
I can't read music notes but been wanting to delve more towards the music composition side but i lack the knowledge to do so.
Anybody has any guitar teachers or short music courses to recommend that focuses more on composition?

If you can't read music notes, then you can't write music compositions on manuscripts. Get back to basics, join contemporary adult music courses focusing on note reading exercises. Experiment on music software to further understand time value of notes (Finale, Sibelius, Encore) and see whether you are able to do some simple compositions. FYI, reading (playing) music notes and writing music notes are two different disciplines. You can be a virtuoso in playing but a novice in writing them and vice versa. Hope this helps.

Totally disagree with you on this matter. There are certain limitations to the tabs eg. the time value of each notes. To compose a melody in a person's head is not that difficult, but to write it down and make another person understand what you have written is not easy. That's why time values eg. semibreve, minim, crotchet, quaver, semiquaver are "invented" so that they are universal and can be understood by another person. The most basic thing is to have an understanding of time signatures & values, rest notes and tablature notation. Then only you're good to go.

There are free software (and paid versions) eg. TuxGuitar, PowerTab editor, Guitar Pro etc that allow us to write down tabs by just keying in the numbers to each tab lines but still requires basic knowledge about time values of each note.