This will be a three prong approach:
A) start practicing to learn to play a cool instrument, entertainers usually stick to their own kind. You're at an advantage, being 14, you have time to learn to be really, really good before this person can legally date you when you're 18.
B)Keep this person in the back of your mind and date other people in the meantime so you can work out the bugs of awkwardness dating. Date lots of different people, but never go too far with them and never devote yourself to them and NEVER say "I love you" to a teenager. This is practicing for dating.
C)Do really well in school, it's absolutely cool these days to be a "cool" "nerd". It's absolutely astounding to be intellectual and be kick a$$ at an instrument and comfortable around the opposite sex (or same sex depending on where you're coming from).
The best thing you have going for you is time. When you are 18, have a diploma, be accepted to college, be great at your cool instrument and be super comfortable with dating. The famous guitarist is only going to be 28 and probably won't be as famous by then, AND because you'll be so cool, they will overlook the age thing, after all it is just a date.