Should I send this text: "Hey (her name), although we have known each other for a long time, we have not really talked much and i would like to get to know you better and talk to you more :)" to a girl so that we can start talking around school?

I don't see what could go wrong with that.

Bear in mind that she could be the kind of person that's just generally rude to everybody, and if she does have that kind of personality, expect some back-talk in her response.

Otherwise, you should be good to go. Remember, just keep your cool and act natural. Acting like somebody you'd think she would love will only make you more nervous.

Yes, I think that would be fine! Hopefully you get a good response! Good luck!