You cannot say, without seeing a map with her house and the surrounding avoids, that there is no reason to fly over her property. It is perfectly reasonable of her to ask. It may not be perfectly reasonable to grant it. The UK LFS contains an incredibly complex mass of regulated avoidances of various sorts. In some places, one more can have effects out of all proportion to its simple dimensions.
When I was young, I used to go horse riding near Dyce airfield. The horses were completely unfazed by aircraft (the occasional Dakota or Chipmunk) or the large noisy steam engines on the railway that backed on to the stable. They did, however, freak out at the arrival of one of these new-fangled devices - a deisel locomotive.
I suspect that horses living in a well-used part of the LFA get used to jet noise in time. Certainly the horses around my airfield don't seem in the least bothered by a large helicopter cavorting at 50-75 ft, as we have been doing every other day or so for at least 30 years.
Sven