Your budget might not be ideal for what you plan to do with the laptop but it is your budget and you can get a laptop that will easily run the software you want. Uploading/downloading are not demanding tasks, the same for most of the usual student work and light entertainment pursuits like music, movies and video.
Keeping your budget in mind, here a few options that should be a good fit.
@ Dixon's or Curry's: LENOVO G570 15.6" Laptop £400
Also available online Lenovo G570 £390
If you don't mind playing the cash back rebate game: Samsung RV520 15" notebook £417 / £367