Realistically - whatever Google says, it will take you three days to drive your UK itinerary. Also, I wouldn't bother with Cardiff. And adding Ireland will add minimum two days to your itinerary.
I agree with Grynch.
Roads, even big ones on the European continent, are nothing like the roads you have in the US (so i'm told, never been to US).
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Living it up on the edge ... of civilisation, within the southwest coast of
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