At Cambridge it will be nigh essential to have evening dress. ignore comments from Hong Kong, our senior Universities, Cambridge, Oxford, Durham and one or two others it is expected. A dark lounge suit would not cut it, if you were not refused admission you would feel stupid. Chobochobo is absolutely wrong. NB I speak from experience:
So that said:
Your suggestions for the evening dress it self are fine, but
no flaps to the pockets or having them picked out in silk or...