A "catch-phrase-list" won't do, because it will sound like you used a "catch-phrase-list". Watch some british television, and if, against all odds, after that you still want to continue down that dark path ... voice-actors that can do proper british can be found where ever voice-actors can be found. and good ones aren't cheap (and shouldn't be). /snark-off

Are you sure you can't go without voice-acting for the time being?

It's either pay someone to do it right or don't do it.

You can make you characters deep and relatable without any dialog at all. There are many ways to tell a story.

I think through all the options. I just wanted to ask, maybe there are ways that I do not know about, cheeper secret ways, and even wanted to know the attitude of the players to the presence of an accent in the soundtrack.

For myself I do not notice this at all, it even becomes nice when games are spoken in my language instantly.