Keep your hair on stotRE. I have had trouble getting potassium permanganate from some pharmacies. It will be down to the people running the place, and what they think you are going to use if for. Some stock it behind the counter and are less than keen on handing it over if they suspect you are going to play pyromaniacs I couldn't buy it for love nor money in Bath back in 1998, well before all the current clampdowns on chemicals.
As said, the ratio is important, and it is better to err on the side of too little glycerin than too much.
I have never really considered this a valid method of fire lighting given all the problems involved in getting the reaction to work and in storing and transporting the ingredients. Glycerin leaks, crystals stain things, or get wet, and it won't work well in the cold. Sure it is a nice party trick, and it gives you a delay type fuse, but neither are needed for bushcraft. Matches are just easier to use, easier to pack and more reliable
As said, the ratio is important, and it is better to err on the side of too little glycerin than too much.
I have never really considered this a valid method of fire lighting given all the problems involved in getting the reaction to work and in storing and transporting the ingredients. Glycerin leaks, crystals stain things, or get wet, and it won't work well in the cold. Sure it is a nice party trick, and it gives you a delay type fuse, but neither are needed for bushcraft. Matches are just easier to use, easier to pack and more reliable