Yeah, that's helpful, cause I didn't have a clue what you were talking
about.
If you tag the text as English UK rather than English US, you can run
spell-check and it should help you fix the spelling.
If you need to use this doc in two contexts, probably do a Save As and
change the language formatting in a copy of the doc.
To change the language formatting, cntl-A to Select All, then go to Tools |
Language and select the new language.
If it is a complex doc with headers/footers, etc--you should probably
redefine the base style in use instead of applying the language as direct
formatting. See here for how:
http://shaunakelly.com/word/styles/ModifyAStyle.html
And here if you don't know what a style is:
http://shaunakelly.com/word/styles/TipsOnStyles.html