I hear ya viper, I would of loved to work in astronomy but I simply don\'t have the brains for it. So I just remain a fascinated observer from the side lines.
I read one theory about colonizing was to send robots with frozen human embryos to places we might want to colonize. Or building a ship the size of a city that could house generations of humans. But as you already said, finding a fuel source to support a craft like that is impossible at the moment, let alone trying to fuel something as big as a city.
I watched Sunshine last night from Danny Boyle (he made Trainspotting / 28 days later). Its about 8 astronauts trying to deliver a gargantuan bomb to the core of the sun to reboot it pretty much, sun is dying and earth is left in a solar winter. I would recommend checking it out if your into this stuff, or at least the first hour of it. The 2nd hour turns into a horror / slasher movie for some reason. But the first hour when the story is mainly about the vastness of space is really interesting. Its science fiction not science fact in the least, but the effects aren\'t all glitzed up hollywood style. Visually, at least for me anyways I found it believable, as in I found myself saying "Yeah, I could see it looking like that."