I know im not 13 but i cycle 3 miles to and back from school(6th form whatever). Saves me £14 a week i can spend on drink(unlikely= parents job :P) and games mostly new cycling stuff.
I use my roadie. Focus Variado 2.0. Although I have a £80 lock for it. It some thieves tried my last lock and failed on a epic scale - twice.On both occasions they nicked someone else s bike which a poorer lock. Anyhow got a new lock and not had any trouble since. Also the coppers got the thieves so np there anymore.
I do 8 miles to sixth form, definitely the benefits are huge. Saves me £80 a month, and also saves me 5 hours a week which would otherwise be wasted waiting for buses. On top of that, there are no crying babies with lost-in-space mothers to stress you out for the whole journey.
As a bit of an insight, I would do 0.7 miles to school before, simply for the reliability factor of it. Buses being buses meant I had to leave 25 minutes early, and even that wasn't enough on occasion - the bike let me do the journey in 5, consistently and without fail.
That holds true today; I can safely leave at 7:30, knowing I'll arrive at 8. If I'm not on track, I can just speed up. It's great.
Plus, it's also a good training regimen.