There are a lot of novice PHP coders that dilute the value of this market. As web becomes bigger and bigger, web developers will be that much more desired, however PHP would only be a part of that totality - but vital non the less. It's a very secure job if you are good at what you do. However as ServerStorm stated, it won't pay as well as some other languages that are less common/require more discipline to get off the ground.
If you have no experience with programming at all, you'll have a rough time - particularly w/o a job. Unless you got a huge savings to support yourself, this isn't the best time to jump in, in my opinion. I would personally recommend finding a job to support yourself and do this on your free time till you are proficient enough to work as a PHP developer - which will be at least 6 months to a year depending on your speed of learning and effort you put in.