An Alternative Survivor's Guide to the United Kingdom

[Sanjuro]

The Grob 109 is an ideal post-apocalypse aircraft because it can use minimal fuel- given a good thermal day it only needs to use the engine for launch, then glide.
Gliders and sailplanes could even be used without any fuel- bungee launch from a suitable hillside, and again given suitable weather you've got a 150mph recon machine, which is almost invisible and silent...