Depends. I suppose you need to consider the rest of your grades and see how they compared to the average at your school.
If you have mostly 8/9 grades, I don’t see any real problems unless you are planning to study English language at Oxford or Cambridge. As such, if you are applying to an unrelated subject to English language at Oxford or Cambridge, I would imagine you’d be better off focusing on your A levels rather than resitting.
I think also it may be a bit late to be entered for this year’s November resit series (though I could be completely wrong - ask the head of the English department at your school), so if you do resit, you may have to resit during May/June of this year when you are most probably preparing for the end of year mocks that may have some bearing on your UCAS predictions. Your A level predictions are perhaps even more important to worry about, at least in my opinion.