I want to write a cookbook. Of course, all my measures are American. I wonder if I should find British equivalents and published a British edition, too.

[KS] If you want to publish in the UK (and this will probably also be the case for places like Australia), you'll certainly have to change the measurements, but you should also get someone to check over the names of ingredients and their availability as well as possible substitutes unless you want to confine your readership to people who live in the major English cities. For example, I live in a small city of about 250,000 people with all the major supermarket chains but the nearest source of buckwheat flour for me would be a 90 minutes round trip.

It's a source of constant irritation to me that any internet search for a recipe draws you to lists of ingredients in US imperial units, mostly because I can never remember what a cup is. One gotcha to be aware of is that US pints are smaller than UK pints (16floz instead of 20floz).

For ingredient substitutions my procedure is the following. First, look for something in your cupboard that you think tastes like the missing ingredient. If that fails, look for something that looks like the missing ingredient. If even that fails, look for something that sounds like the missing ingredient.

My gelignite-based desserts have made many a dinner party go with a bang. (Although they do have the advantage of being strictly vegetarian).

[KS] don't change the measurements! Just include imperial and metric along with US cup measurements... Lots of recipe books and websites do this. Then you only have to produce one version.
[INJ] Try your local windmill for buckwheat. Alternatively, I can bring you 5kg next Saturday. The buckwheat is free but it'll cost you merely the price of the ferry ticket.

[Pen] That's the distance to the watermill who make the flour I usually use for breadmaking. I can buy the normal white, wholemeal and malted grain from my local butchers, but more specialist stuff is only sold at the mill.