iPhone autocorrect (british)

Correct. My hardware keyboard is Spanish, which is what I'm used to. Then switching between Spanish & English using the 'globe' key I get a Spanish or UK English spellcheck, depending on what language I want to write.

To deal with words that end in "ize" instead of the "ise" that is now in your UK English Keyboard, you need to program your iPhone's autocorrect. I found the easiest way to do this was to type the word (eg. organization) a couple of times and not let the autocorrect change it. Eventually Autocorrect recognized that "organization" is my prefered choice and gave it as the option. It still says that it's spelt wrong, but and the end of the day, who cares? I find it more annoying for autocorrect to place in the US spelling than inserting a wavy red line at the bottom of a correct word.