The rule of thumb for a mass retaining wall is that the depth of the base needs to be about 1/3 of the height so at the base the thickness ought to be something like three layers of block - 675mm wide. A beast like that really needs designing.
@Jack4 yes your last sketch proposal is better, at least an acceptable proposal assuming the levels work! Who is submitting the Build Over/Near Agreement to the Water Company? You or your architect?If you look on your water company's website you should be able to find all the criteria you need...
On the face of it, given the reasonable advice already offered, it seems hard to see how the thread could become derailed and continue for several pages. However ....
No I wouldn't expect the foundations to be inspected, unless say the house was very old and/or the foundations were questionable. The end of a beam sitting on a wall spreads the weight over several metres of its foundation.