Help with VO and SIRI, In (JB), mode.

I am needing help with siri and voiceover. I really want to use the high quality brittish voice but, if I do with my phone in normal mode, (Not Jail Broken), Siri thinks I'm actually in Britten. So, it says that I can't look up anything unless it is set to US. So, my question is If I set the phone to have the high quality brittish voice, is there some kind of tweek or something that will make siri think I am still using the US region. I want to use the voice for VO specifically.