AGGS has a boundary limit of 8 mile radius from the school, but in in the last few yrs girls have come from 6.1miles in 2012 , 5.8miles in 2013, 5.3 miles(I think) in 2014 so the net so to speak seems to be closing.
Theoretically one can apply from anywhere in the U.K but to be in with a chance, realistically you need to be within the 6 mile limit.
your daughter will have to score at least 334+ age standardised.
AGGS is a little odd it also standardises within it's own self-select cohort in order to differentiate between very able students not the national cohort
after the 2nd of march you will get an idea where the 2015 cohort boundary line will be, I have a feeling it could be even tighter unfortunately due to some "trouble at the mill" with Lymm High and quite a few youngsters are applying to the Trafford Grammars last yr, but things are stabilising there, so the boundaries may move further out again for the 2016 cohort