I've been teaching guitar, bass and music theory for 30+ years.

No doubt you want to get a foot in the door fast.
Learn some power chords and play along with your favourite records in the first lesson.
Don't feel abashed about lacking any previous experience. It's not neccessary. I've taken many adult total beginners up to public performance level.

Pick your favourite tunes to learn from whatever your ability.
Any tune can be arranged to accomodate your current ability and you can add the details as you become more proficient.
One of the great joys of playing an instrument is to become able to capture the emotive force that the artistes you so admire can evoke.
Discover how they do it. What scales they use, how they create their sublime musical phrases, what their vibrato is like, what ornamentation they favour.
Every tune will have it's informative nuances to study, be it timing, scales used, rhythmic features...

Learn a few famous solo's, how to join a blues jam, borrow a few of their lines to bedazzle your audience.

Guitar Grades.
Rock & Pop, Classical, Acoustic...

You don't have to do them but it's nice to be able to guage your progress and if you're hoping to do a GCSE in music or go to a music college being able to show your credentials can be essential to getting an audition.
Steel string or nylon, folk, country, blues, Rock or pop all are covered by the various examining boards.
My students have a 100% pass rate across 30 years.

Having been awarded the David Riley memorial prize for the best Grade 8 entry in the West Midlands in that year (1991) I can help you get up to speed in the Classical genre.

The ability to follow and write a chord chart greatly aids your understanding of the tunes you're playing, helping you to rehearse and arrange a set and enabling you to join other musicians or acts at short notice.

Reading music is not absolutely essential just very helpful. It's advantage over tablature is that it'll tell you the rhythms, making it possible to play a tune you don't already know and helping you to work out difficult bits more easily.
You'll be able to see at a glance how the melody and harmony interrelate which makes things easier to remember.