I used Zippo. I didn't die. Is that available in Ireland?
As for lye it should be readily available online or in store. It's a common home chemical used for cleaning. Any brand will work, cause all caustic lye is the same compound: sodium hydroxide.
Personally I think it's better to just make a tea and skip all the fuss with extractions.
I don't want comfort. I want God, I want poetry, I want real danger, I want freedom, I want goodness. I want a clever signature.