Oxford computer science
It seems best you would get is either C++ if you are lucky or Java if you are not. Sorry but it all seems to be more theory driven then anything worth while.
Cambridge computer science
These guys at least tell you what languages they will teach you, ML and Java... Never even heard of ML, while Java, well I hate it, but there are jobs for it.
In the end of the day, those courses seem to be more theory based rather then any actual skill. So in the end it depends where you want to find a job in. But working with hardware or embedded systems will be "closed" to you on either of those courses.
But like I said, do what you want to do, but most employees who are not idiots now days, would not pay attention to what university you went tom, but more what skills you have, and unfortunately those courses will not give you many skills which are useful outside university.
Not digging into the "elite" universities, I couldn't care less. Just saying that it depends what you want to go into really. If you like hardware, device drivers, embedded things, or just plain C, this is not the course for you.
Regarding actually applying to it, I have no idea, sorry. My experience in applying to them was to take a leaflet, look at their GCSE level requirements and go look elsewhere, my GCSE's suck.
Edit: While in any university, during summer, especially if you go home. Look for local computer related companies where you can "work for free" at, basically approach them and say "I am studying so and so, and I want to gain some real experience working in the industry." Chances are they will take you on (mainly this free thing), and it will look amazing on your CV, shows you are interested in the subject rather then spending your summer drinking yourself stupid.