I'd sure hate to waste beer on a radiator.........but I have put high proof Vodka in one once when a cold snap was announced late on a Saturday nite when I lived in Lander, Wyoming (-40°F)
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The usual USA antifreeze solution (good down to -37°C/-35°F) is a 50%/50% mix of Ethylene Glycol and water. It would probably do the job for the English Isles - won't work in the northern tier of states here - or up in the mountains. The stuff is very poisonous and has a sickeningly sweet odor - several of our states have laws making it mandatory to infuse it with a horrible odor. Anyway - keep kids, pets and small animals away. There is an alternate available that isn't quite so deadly - Propylene Glycol - but none of it needs treated without due care.
For water - use distilled water if you can - it will not leave lime deposits in your engine like hard tap water will. It is available by the gallon stateside at the grocery for almost nothing. Out of the container distilled water actually may be a tiny bit acidic due to abosrbing atmospheric CO² - but there is a simple way to make it neutral (espoused by our EPA) which is to add one drop of household ammonia per gallon. Pretty simple chemistry and easy to implement.
Steve Metzger Tucson, Arizona