Good luck with the interview!
And try not to be so nervous - you know your job. It shows initiative to apply for a higher position, and it shows that you are loyal to your company by wanting to move up the ladder there.
As a high-level manager at my work, I am always impressed by the people who step up and want to take on more responsibility. So, as you said - even if you do not get this specific job, just the fact that you are going for it will bode well for you in the future.
That is awesome! You are getting ALL KINDS of great stuff coming your way, lady!
Now go home and celebrate with some sparkling cider and nookie!