if u want good battery life too, u can check out "nvidia optimus" based laptops... those have switchable graphics so u can change to low power intel graphics when u dont need the power of dedicated graphics... acer "TimelineX" based models have it..
also check out notebookcheck.com ... in that go to search , enter the max price (in pound).... and it will show u all laptops under that along with reviews..
I suggest Dell Inspiron 15 or Dell Studio 15.......I'm using studio 15 now and i'm quite satisfied....though u cannot hope for anti-aliasing....the graphics are pretty good.....I think it is comes with a 1 GB nvidia graphics from the factory itself....when i ordered,i had to customize it.......It has nice batters life...though not much.......and the service is EXCELLENT.........the best part is the screen......nice and big.....
To be honest, there are none which will satisfy your needs under 45k. All such laptops are accompanied by crappy, entry-level graphic cards. Raise your budget or go for a desktop. I did read a news though regarding MSI releasing an external graphic card solution for lappies which features en external ATI Radeon HD 5670 1GB card.