Oh no, I was thinking that too but I ended up just going with the flow and enrolled at Imperial because I wasn't 100% sure then about medicine, which I sort of regret now... but it is what it is and I'll try to use it to my advantage and hopefully partake in some medical research in a UROP at Imperial. I was orginally thinking about dropping out but I'm worried that might come across badly when I apply.
I got A*, A*, A, A in Biology, Geography, Chemistry and Maths respectively - are these not strong enough for Oxbridge?