I agree with @DadOfJerseyGirl that your chances are in the low single digit percentages. For an international student applying to Stanford, MIT, or Harvard that is actually quite good – but you will most likely end up at one of the excellent universities in the UK.
A bachelor’s degree from the UK plus a master’s degree in the US is likely to cost you less in total compared to just getting a bachelor’s at one of the top US schools without financial aid.
It makes sense to me that you would only consider coming to the US for a very highly ranked university. The UK has quite a few very good universities.