Hi craigh.
Unfortunately there's no lens that is good at everything. The Tamron 18-250 is an excellent general purpose or travel lens, but there are bound to be some compromises with anything that has such a wide focal length range. The maximum aperture is a little small, it isn't the sharpest lens in the world (although perfectly adequate for most purposes) and there's no image stabilisation.
However, it's a good start that will do most things, and you can add to your lens collection in due course for more specific applications. The Tamron will always be useful if you want to travel light or need to avoid lens -swapping. For telephoto, without spending a mint, I'd recommend the Canon 70-300 IS which is much more useful, especially for hand-held shots, than the standard 75-300.
So I'd start with the Tamron and build on that, but that's just my 2p.
