| | Re: how the language is used in the UK
I'd use "variety of English" rather than "dialect" in this case but that's just quibbling over terminology. The answer to your question is yes - lots of people might use "he don't" - for example in London where I come from. I've never heard "in Sunday" but wouldn't want to say that it doesn't exist in some variety somewhere or other.
I suspect that you didn't find much when you were searching Google because your search terms were too wide. You'll find a certain amount under wide searches like "varieties of English" or "English dialects", but try narrowing them to eg "London dialect" "Yorkshire English" "Scots dialects" "West Country English" "Norfolk dialect" - or whatever region you're interested in
If you're particularly interested in London, try "Cockney English" too, and also "Multicultural London English".