was -7 sheffield all night...I know I was out in it......brrrr
However bottles in a building will be somewhat protected from the lowest temps, and if you can increase the protection by STANDING your bottles on some insulation ( towels sheets and or newspapers) , throwing as much insulating material over them the better.
Beers don't like being frosted so try and make sure your shed /outbuilding whatever is frost protected by using a greenhouse heater ( parafin ) or similar little heater.
We do what we can and most of the time our beers will come through it unharmed, but we can all try and minimise the fluctuations and the lowest temps by taking simple little precautions.