it doesn't really make sense to buy overlapping focal lengths for about 99.9% of the time. when you use the tamron or even kit lens.. you have the option of zooming from a wider angle, 17mm to a more narrow angle of 50mm. if you get the canon 50mm lens, thats the only length and field of view you will get. these are called "primes" because there is only 1 fixed length. so like what was said above, but the body, the tamron and use the shit out of your camera and learn it inside and out, looking up articles online, taking lots of pictures, seeing how all of the different variables work together. this is the "learning curve" that most refer to when someone switches to a dlsr. its not like a point and shoot where you turn it on and its good to go.
basically my advice...get the tamron non vc, you won't need it, a decent memory card, and the t2i body. then when you start using it a lot, you will know what you want for your style of shooting of then you can upgrade piece by piece after that