I did this exact thing - learning php, mysql and a bit of javascript from scratch to do a site. My experience was that if you put some effort into it it's not that hard.

The sites that I have used as references are primarily http://www.php.net, http://www.w3schools.com and http://www.mysql.com/

And of course this site that will answer all my questions if only I know how to ask: http://www.google.com

Good luck :-)