Yes, that's why I suggested lessons - it's VERY likely they are available 'reasonably' cheaply at your school - and it means you get time out of lessons!
Have lessons for a number of weeks, and if you enjoy it, then see about getting a guitar.
Here's how it worked with Melissa - who's an only child.
Started piano lessons about 6 years old, after a number of months we bought her a second hand keyboard to practice on at home.
12 years old, year 7 at secondary school, Charlie was wanting to form a band, so because Melissa played piano he asked her to be the bass player?. At that time besides piano lessons she was also having singing lessons and keyboard lessons, so we swapped her from keyboard lessons to bass lessons. She had about 4 or 5 lessons then it was the summer holidays (six weeks with no lessons), so we bought her a bass and amp. By the time she went back to school she'd already done a gig and a recording session on bass!.
Also in year 7 she started flute lessons at school, where they lent you a flute free for the first year, so after a year we bought her a flute as well.
The music teacher asked her to start guitar lessons as school as well, so she started lessons at school - but we cancelled them when the prices doubled!! - and she went elsewhere for guitar lessons. I borrowed a guitar for her, and later bought her one.
Notice the common thread throughout that story - don't buy the instrument until you're SURE they are going to stick with it!.
BTW, she still has piano and flute lessons, but just teaches herself on bass and guitar.