Distribution Board for 380 Volt 3 Phase, Neutral and Earth

My building has 3phases 380Volt coming in, a 3phase meter, with 60Amp mains breakers. However it is currently only wired for single phase. The lights on one phase and neutral, plugs and geyser on another phase and neutral and one phase not used.
I believe South African wiring standards are similar to those in UK. I have bought that FP1 with TNC111 Active DRO (more later) and now I need to get it juiced up. My thoughts presently (I am definitely open to better suggestions, actually asking for them) are to get the 5 wires into a distribution box separate from the single phase DB I already have. Do I need, in this order, a 3phase circuit breaker say 60Amp, an Earth Leak breaker then say 3 (for future needs) 20Amp circuit breakers feeding into 5 pin sockets. I prefer to have switched sockets. It all seems like too many contacts in series. Living in a small town in the a##hole end of nowhere, guys like electricians and plumbers are dodgy to say the least and I would like to have some educated input into the wiring or do it myself.
Thanks,
Ant
.

A lot of three phase power outlets round here are only 4 pin with three phases and earth. This is great if you only want to use all three phases, if you pay the extra and have three phases, neutral and earth with 5 pins, you have a lot more flexibility, as you can now get single phase from the same power outlet. Be careful with a three phase earth leakage device as you can still be electrocuted phase to phase and it won't trigger, unless there's a path to earth.

SAG thanks for the heads up re electrocution, phase to phase really bites. BTW I liked your line boring bar. The Deckel needs a Neutral connection for the coolant pump and DROs. Bump... Nobody has any input about the DB Board?

Antman, I happened to be talking to a retired South African electrical engineer today, will see if he can give some input.