If you look at the first section of the CAP696 you will find a list of definitions.
Dry Operating Mass (DOM) is the mass of the aircraft with no usable fuel and no traffic load.
Operating Mass (OM) is DOM plus take-off fuel.
Take-off Mass (TOM) is OM plus traffic load.
So TOM is DOM plus take-off fuel plus traffic load.
There are various factors which can limit the alowable TOM, allowable take-off fuel, and allowable traffic load.
so we can say that maximlm allowable TOM equals DOM plus allowable take-off fuel plus allowable traffic load.
For CG purposes it is enough to know that,
MAC is the average chord length and it occurs at a specific point along the span of a swept wing.
The leading edge position of the MAC (leMAC) will be specified as a longitudinal position relative to the CG Datum.
The CG position expressed as a %MAC is ( (CG position - leMAC) /MAC Length ) X 100%.