Of course, Oxford and Cambridge would be expected to have good programs.
http://www.physics.ox.ac.uk/Theory/nuclearstructuretheory.htm
http://www.physics.ox.ac.uk/Theory/currentresearch.htm
http://www.phy.cam.ac.uk/research/ - but does not seem as strong in nuclear physics per se.
But there are also
http://www.np.ph.bham.ac.uk/ - U of Birmingham, School of Physics and Astronomy
http://nuclear.gla.ac.uk/ - U of Glasgow, Nuclear Physics
http://nuclear.ph.man.ac.uk/ - U of Manchester, School of Physics and Astronomy
http://www.ph.surrey.ac.uk/cnrp - U of Surrey, Centre for Nuclear and Radiation Physics
http://ns.ph.liv.ac.uk/ - U of Liverpool, Nuclear Physics Group
http://www.ph.ed.ac.uk/nuclear/ - U of Edinburgh, Nuclear Physics
And there are many schools on the continent,
Delft U in Netherlands, http://www.rrr.tudelft.nl/live/pagina.jsp?id=5cdcf711-51a7-4c18-b780-51c006225f66&lang=en
U of Stuttgart, Germany, http://www.msc.physics.uni-stuttgart.de/syllabus.html
Is one looking for grad school or post-doc programs or both?
And is one looking for experimental or theoretical?