If you're limiting your budget on glass, why dont you go for a cheaper body to begin with? 30D or 450D will still be a good body, but you can get better results with a 30D and a good lens than a 40D and a poor lens. Likewise the 400D or 450D. I would seriously think about looking at lifting your budget for glass, possibly to around the £200 mark and that would put you in the market for a Tamron 17-50 F2.8 non VC, or 17-85mm if you wanted the extra range. I think Sigma also have some options in this price bracket.