Link to my Recommended Books store on Amazon:
The AB Guide to Music Theory Vol 1:
The AB Guide to Music Theory Vol 2:
These videos will take you through the ABRSM syllabus of Music Theory from Grade 1 to Grade 5. I will try to cover all the theory which is practically applicable to playing and understanding music, leaving out some things like meanings of Italian/German music terms which are part of the syllabus but not so much related to playing Guitar.