We tend to prefer Torrontes or Sauvignon Blanc.
Our preferred countries are Chile and Argentina, although anyone living near a branch of Oddbins sould check out the Greek stuff that has been produced in recent years; Notios is always good, and if you don't mind stepping up towards the ten quid mark then there's the astonishingly lovely Amythystos:
I know people who will quickly diss French wine, but there's a lot of quality French stuff at all price ranges, so don't be too hasty.