2.5 kN/m2 is fine, according to BS6399 Part 1: -
The imposed floor load given in Table 1 with class C (public buildings used for public, institutional and communal dining rooms and louges, cafes and restaurants) is 2.0 kN/m2 and a concentrated load of 2.7 kN. However, there are some other caviat notes which should be read such as those governing places where overcrowding can occur.
Shops, by the way, should have been designed for 4.0 kN/m2
Hope this helps