Thanks a lot for your responses.
24-70 is out of my reach for now as justifying that kind of expense to myself will be difficult keeping in mind my little knowledge about photography.
I think I have made up my mind that I will go for Tamron 17-50mm f/2.8 Di II LD Aspherical IF SP AF (£245) and EF 50mm f1.8 II (£65) through partner sites (provided they can offer me at this price as this is market price).
Now my only concern will be long range zoom 70-200 which I will buy from canon or sigma having IS or OS later.
Bob, Thanks for your advice... but unfortunately 17-85 canon review elsewhere is not that great (too much distortion at 17mm etc).. it is always being compared to kit lens and I want something much more than kit lens but cheap..
Tom, Thanks for the review of Tamron...
luis, Thanks for 50mm review..
I will appreciate if anyone of you can give me some links to master my 400d and other bits in photography step by step..
Not to mention that this site and all of you guys rock...keep up the excellent work.. you all are so helpfull..
400d body only