It must be weird having a different accent to everyone around you, the only odd thing about the way I speak is that I say th as f, so when I say think, it sounds a bit like fing, I just can't help it though.
But yup, he's right, I can't really describe the different accents, but theres the Cornish accent, Liverpool accent, Scouse accent, London accent, Birmingham... it carries on and on, I'd try describing them to you but I'd do a terrible job.
Well its awesome that you're able to play a wide variety of instruments, I don't think I picked up a guitar until I was 15, and that was because I'd joined a friend's band (without even knowing an instrument, ah well), that band went nowhere, I can only remember 2 ideas for guitar riffs I had, one was just the open E and A strings played with single strums in succession, that sucked, the other one was an A chord with a strumming pattern of down up down repeated, that one also sucked. I wonder how the 15 year old me would react if he saw the 18 year old me play lol.
Being 15 leaves you with a ton of time to find a band if that's something you'd like to do, I wish my band came together when I was 15, it would have gave us a head start. Here's a mind ****, when Paramore released their first album the drummer was 15, that's really, really weird.