Ring or radial circuit for garage workshop
I think I have an answer to my question now based on some research. So if a 16A breaker is installed and the maximum load I have is around 3.5 KW, it won't trip whether it's ring circuit or radial circuit. However I decided to put it into a ring circuit in the end because of the way I wired my workshop. The wires are surrounded by insulation and going through wall studs. As a result it's not the best setup for heat dissipation. Based on this table my wiring method reduces the current capacity of 2.5 mm cable to only 13.5A using radial circuit, which is not enough for my need. It won't trip the breaker but it'll be a fire hazard.  If I make it a ring circuit I'm effectively doubling the cross section of the wires making it 5 mm cable. With my installation method, it can sustain around 20A, which suffices my need.