You can definitely be self taught. I taught myself to a high enough level to then attend university and study music. I did come from a musical background and already play the piano so I admit it's a bit different if you've not got any prior musical experience.
However there is a wealth of musical lessons around.
Try out everything! Video lessons, text lessons, have a tutor for a few weeks, etc and find out how you enjoy learning. A good tutor is very valuable however I wouldn't say they're essential at all.
With students I've taught I've found it's best to learn some very simple songs (Open chord based songs) that you enjoy first. Why? Because it tends to grab your attention and make you realise how much fun you can have playing the guitar.
Once you've done that... then it would be time to expand and learn scales, arpeggios, chord shapes, modes etc.
But yeah... lots of advice given in this thread.
I'll try and write something more complete later one when I'm not at work to explain how I learned and how I think you could learn (and adapt your learning to enjoyment, as you need to enjoy playing or you won't ever practice).
For one starter question... what kinda music do you enjoy listening to at the moment?