As long as you do well in English they literally won't give a crap, I know someone who got AABC at AS and got in for PPE, which is miles more competitive than English.
And lol at the person above, getting a D is practically a fail, even if it isn't an 'official' fail. No unis that I know of specify that getting a D is fine, so if getting a D isn't useful for your uni application then it might as well have been a U.
But yeah overall OP, getting a B is absolutely fine for Oxford as long as you do well in the relevant subjects. If it were Cambridge though then it may have an impact, depending on your other subjects, because I think they look at your UMS across your top three subjects.