Please help 110v distribution

[Shakeout]

Hi all, Ive been asked to supply a 110V distribution board containing 1 x 40A and 2 x 32A DP circuit breakers. The company ordering the work has provided a new 12KVA CTE transformer.
Its been a while since I did anything like this so I just wanted some opinions on whether or not I am installing correctly.

I have a primary supply of 230V from a 50A DP mcb. from that I run 16.0mm armoured to a 63A DP isolator local to the transformer. I connect LN to the primary and earth to the earth lugs and centre tap.
I then connect 25.0mm armoured to the secondary and run through a local 100A DP 60898 and into the mainswitch of my distribution board containing the DP mcbs. I also take a 25.0mm earth from the centre tap to the earth bar of my distribution board. (the earth is therefore connected from supply-transformer-centre tap-110v disboard)
If memory serves me correctly I willhave 110V between my supply cables and 55V to earth.

Does this all sound OK to you guys? Aslo, do I use 2 x brown cables for the 110v supply to dis board as neither are a neutral?
Please go easy on me, its been a while since I tackled this.

Thanks.
(Apologies if this posted twice, tried a couple of times but couldnt find it)