Is a CS degree for me?
In the UK, some of the universities to study at are Oxford, Cambridge, York and Imperial College London, though this list will vary depending on precisely which topic you are interested in. The group of Abramsky at Oxford does research in Quantum Computation, so going there and following courses he offers (and related ones) would certainly help you reach your goal. 

It would be a good idea to go through the web sites of the computer science departments of the above mentioned universities and see whether they offer courses (or even a program) that heads in the right direction. Look not only at the descriptions of courses, but also of the personal web pages of the researchers, who will often have some description of their research interests, which may differ from the courses on offer, but will be available to study as you enter later phases of your study.