>>1 you can get it from Morrisons in the UK or other large supermarkets like M&S and possible ASDA and Sainsbury's.
More and more shops are stocking Asian food, and even bits and pieces to make the food i,e like sea weed rap for making sushi.
If you are looking some Japanese food stuff you can't find locally here's a link "copy and past it" -
http://www.japancentre.com/
hope that helps. :D