Most spellcheckers are US English. Here's one that knows how to spell colour properly. ;D
http://www.spellcheck.net/english_united_kingdom_spell_checker.html
It's not the spelling I have a problem with, more a case of fingertips that are very wide and hit keys both sides of the one I want.
Do you know of an online cosmetic surgeon who could help ? ;D
You can get keyboards with bigger spaces between the keys. I've lost count of the times I've typed 'ypu' instead of 'you'. :-)