The choice of camera is the big decision. You can get EOS 1000's for £300 used, with a kit lens (for example,
this one) but, seeing as you can buy a new one for £350, I'd rather buy new. Frankly, that could be the subject of a whole thread in its own right.
The Tamron is a decent lens. The most popular lens of this ilk is the Sigma 10-20mm which performs a little better as well, so that would be my choice (the f/4-5.6 version, not the pointless and more expensive f/3.5 one).
Don't forget that you will need a filter holder and adaptors for the filters and, looking into it, I'm not sure that Kood will supply "Z" sized filters, which you'll need for shooting at wider than about 14mm so you may have to go down the Cokin route there.
And the battery grip. Well, no you don't
need one. If you want one, thats a different matter. Frankly, it won't offer you anything useful if your camera is always mounted on a tripod. Just buy a spare battery (you'd have to have 2 with the grip anyway) and carry the spare battery in your bag.
Tripod-wise, I think the best sub-£100 tripod is
this one. The nearest Manfrotto model is £160 and this one is still better. I've had various makes of kit and nothing comes close to the Giottos models for less than £400.