I'm half-tempted to just post owtheedge.jpg because of the latter part of your post but you're an angsty teen and I've been there, done that, so I'll be nicer than that. Look, some are still trying to figure things out about themselves when it comes to their bodies and sex (even the straight ones) so they won't talk about it loudly and openly. Also I would be wary of using conversations within your own social circle as evidence, I talked just about girls and basically everyone thought I was straight as they come (one exception that I will come to later). Then there is the minor problem with your social circle ≠ reality, now I don't know how your school is or who you hang out with but the unfortunate thing with this is that your mileage will vary and it will vary a lot. Some schools (and then within schools, different years, different classes and different social circles) just are more open when it comes to all things LGBT.
I know, I kind of ended up rambling but I guess I'm trying to say that there is a reason why the It Gets Better Project is called just that. You might not meet any openly LGBT students in your sixth form (then again you just might), but they are there and years later you might run in to them on say Grindr and end up having sex with them for basically giggles (but enough about me for now). But you will end up meeting openly LGBT people sooner or later.
Oh and about the entire exception thing; Me and one of my friends talked about sexuality and things and he said "I almost wish I was bisexual sometimes, what about you? *pointed silence*" And I just hand waived it away because I didn't want to come out to him at that point in time. It isn't the only time I've been offered an opportunity to come out to people who really made sure that they would be okay with it but I didn't. Since I wanted to do it on my terms at a time and place of my choosing, unfortunately for me I kind of suck at choosing a time and a place. (Don't drink and come out kids, especially not in public places, and without checking if your teacher is sitting behind you)
And yes LGBT people are just as boring as everyone else since we're just people, like everyone else is too.