After some advice from the few of you who are involved in this game. Basically I have been asked to design and build a pool outbuilding. Changing area, pump room and large covered area for a table and pizza oven etc.
The design and build isn't an issue. My concerns are the depth of foundations required. My head says to go with what is required for a single story extension. The ground is on clay but is near some trees. So brick dwarf walls around a foot high. The large post/beams I think should be concreted into place in the ground as oppose to fixed to the brick wall.
The floor will be some granite paving which they have left over from some previous building works.