Surely you can get hold of a high-proof alcohol from a scientific supplier? I'm sure this stuff is made an available in the UK, just not on the high street.
If you have any friends who are teachers, they could ask their science/chemistry/biology colleagues for tips. Alternatively, medical professionals might know something - surgical spirit, and all that.
I know that in France a lot of different alcohols are available in supermarkets because they're used for things like cleaning windows and burning in chafing dishes and fondue warmers. Is it possible that such things are imported for French customers over here? Obviously the issue with importing anything is going to be duty, so that's no use.
Finally, if you're up for contacting a full-on perfumery supplier to score a pint of full-strength alcohol, you could contact the British Fragrance Association and ask for a list of suppliers http://www.bfaorg.org/