I agree with the others that going to medical school when you know that you don't want to practice medicine probably isn't a stellar idea. Everything about medical school is geared towards working as a doctor and you'll be detached from the whole experience if you know from the beginning that's not what you want to do.
If you want to go into research of any kind then you are likely to need a PhD. You could go MBBS > PhD or BSc > PhD and both would be acceptable routes, but the latter would be two years quicker.
Do you know what kind of research you are interested in? You can take a BSc > PhD route into just about any kind... from lab science to epidemiology to statistics to healthcare economics to clinical trial design. The only thing you can't do with out a medical degree is treat patients but it doesn't sound as if this is something you want to do anyway.
In terms of the university you go to, research is a big part of all Russell Group institutions. You will be able to get involved in summer research projects etc at any major university but some might be more keen than others in involving undergraduates early on. Remember that most lecturers are on the look out for the best students to work towards PhDs with them afterwards.