Since I am not from GB, I can't really say where to go. However, with any engineering career path, there are the same things anyone can do.
Firstly, I do not know of any university that specializes in propulsion. There are plenty of schools in the US that have aerospace programs with a good selection of classes related to propulsion. The best thing I can think of is to look at aerospace or mechanical programs and tailor your class selections toward your desired career, i.e. fluids and thermal, propulsion, etc...The propulsion field is not a very large one, so it is a bit tough to get your foot in the door unless you get a bit lucky. God knows I was very lucky to get in when and where I did.
Admittedly, a structural position will probably provide more opportunities in terms of employment. Again, if structures is where you want to be, alter your course selections to reflect what you want to do.
One thing to remember is that when you decide on a relatively narrow career path, you must be prepared to move wherever the work is. A lot of people do not want to do that and wonder why they can't find the job they want.