The only recording of Victoria's voice is scarcely intelligible. However of the thousands of her subjects she came into contact with over the course of her life, no one remarked she sounded like a foreigner (though many did on the quality and clarity of her voice), so despite having a German mother and a German governess, her speech was clearly and deliberately given special attention. I don't believe she only learned German after marrying Albert, but I do believe her when she says her first language was English, even if I'm not 100% certain from whom she would have learned it!
Their son, otoh... there are persistent reports Bertie/Edward VII had some Germanic pronunciation, or at least "R"s, and no recording of his voice to support or dispute it. We know he spoke fluent French and German like his mother.
George V sounded like a normal guy. Not even posh. If he could speak German or Danish, I'm not sure what he did with it, considering he didn't like "abroad". May of Teck was considered to be British, name aside, even by British people.
Edward/VIII spoke German fluently, not to his benefit, and I'm pretty sure George VI could too, but, again, no idea what Bertie did with it.