If it's a ring final circuit, this is a non-standard circuit arrangement, and the designer is therefore responsible for determining that overcurrent (overload and fault current protection) is addressed correctly for all possible combinations of current sharing. would it be easier to split into 2 no. 16 A or 20 A 50 m radials ?

When you ask about C32, is that for ADS or overcurrent?

What is the arrangement of the circuit (is it TN or RLVS)?

If it's a ring final circuit, this is a non-standard circuit arrangement, and the designer is therefore responsible for determining that overcurrent (overload and fault current protection) is addressed correctly for all possible combinations of current sharing. would it be easier to split into 2 no. 16 A or 20 A 50 m radials ?

When you ask about C32, is that for ADS or overcurrent?

What is the arrangement of the circuit (is it TN or RLVS)?

32A breaker feeding any  16A sockets for unknown use without fusing down would be unusual, as there is very little to stop overload of any one socket. Two is not unknown in theatrical practice, but in that case the loads are well defined and the loading hopefully understood by the installer.
What drives you to this layout and not say two radials protected at 20A or less instead ? It seems an odd choice, so I presume there is a good reason. 

The 4mm will be fine with the 32A interms of rating, assuming its not in thermal insulation,  and two paths of 4mm feeding each socket seems quite chunky - is the 100m to the far point of the ring - so 200m ring-round, or is the 100m the ring round distance so that the far point is 50m from the origin, and fed by the equivalent of 8mm ? VD may be an issue -transformers droop too.

Also H07 - are you thinking flex then, or is this a fixed installation ?
mike