Hi DanTheMan,
Our Little Reader English Curriculum is only available in two varieties - US (American accent and spelling) and UK (British accent and spelling). We don't have a UK spelling + US accent option.
However, if you are getting the Little Reader Basic kit (or the English Curriculum Pack + Little Reader PRO Key), I suggest you choose to get the US version, then you can edit the spelling of the words where needed (e.g., edit "colors" and change it to "colours").
For instructions on how to edit words in Little Reader, see:
http://support.brillkids.com/hc/en-us/articles/204595114-How-to-Edit-WordsIf you want to replace the word (e.g., instead of "pants" you want to use the word "trousers"), note that you need to replace the corresponding pronunciation recordings and picture audio (audio commentary) too.
I hope this helps!