Suggested by Dan Newton – Under Review
Omnichannel voice has been generally available in the UK for several months however it is currently only possible to use "English - United States" for voice languages. This means any automated messages are not region specific and have a out of place American accent. Other Microsoft products support "English - United Kingdom" specific voices etc.
Status Details
English UK is available for Speech to Text and Text to Speech. Link - Supported cloud locations, languages, and locale codes for voice channel | Microsoft Learn. Rest under review.
Administrator - the link provided is for transcription only. I am referring to the voices available for custom automated messages.