Do I have a shot at Oxford?

lol its how life works, the more people that apply to Cambridge and oxford the better for them.

How is it better to have more and more people applying? How much time and expense do you think Oxbridge already puts into the admissions procees (answer, a lot). It's not in their interests to attract more people that are likely to be unsuccessful applicants. They only want to attract those who have a reasonable chance.

And that's why they are making increasing efforts to be transparent about their processes and also the expectations they have from their applicants.

I can't speak for Oxford quite so much (although @BrasenoseAdm is extremely visible, helpful and honest in their discussions with applicants from what I've seen). But certainly @Christ's Admissions and @Peterhouse Admissions are excellent in the advice they give to students interested in Cambridge.

Hi, sorry, I'm hoping to apply for Chemistry (which would be Natural Sciences at Cambridge).

Predicted grades are A* in biology, chemistry, physics, mathematics and the B is for FM.

Pretty sure four A*s in the first four subjects would be impressive enough on their own; you should seriously consider whether it's worth keeping further mathematics unless you're reasonably confident that you can exceed the prediction and that it won't drag your other grades down (four A*s > three A*s, one A, and one B).

Definitely go for Cambridge over Oxford. Chemistry is one of the few subjects at Oxford that doesn't have an admissions test so you couldn't make up for the GCSEs with that as you would be able to in other subjects.

Hi, sorry, I'm hoping to apply for Chemistry (which would be Natural Sciences at Cambridge).

Predicted grades are A* in biology, chemistry, physics, mathematics and the B is for FM.