If you don't go for an interview you will never get the job.
If you do go for the interview you might get the job. You want it right, then let them know you want it!
I don't quite understand the presentation, is it a on the spot topic? Or you just don't know much about the topic you have to present on. If it is the latter, learn.
Also look internally at what thoughts and emotions make you dislike your current job. If you don't deal with these they will creep up again in another job eventually.