westham,
Don't think anyone's confused.......
The Localiser critical area we have is 1000m in front of the localiser antenna for the A380, which extands on to the upwind end of every runway, rather than the smaller localiser critical area for Code E a/c which is, off the top of my head, 660m, which only infringes the upwind end of one of our runways.
The GP critical area we have an issue with (27L, line ups via SB1) is now, as I said above, a no-go area when a/c are within the protected range of the GP, which is 15nm. It used to be the practice to warn of fluctuations and keep going if it was a nice visual day. Our GP critical areas are the same dimensions regardless of a/c type, but not or Localiser Critical areas.