Retaining dwarf wall for timber frame garden room?

[HHHAMSTA]

Hi All, i'm looking to build a 3m x 8m garden room and maximise the available height.  My garden is raised at the back where the garden room will be going so I'd like to set the building into the raised section which is about 350mm higher at the back compared to the front of where the building will be.  I was looking to build with cavity blockwork which would have been easy to build up the retaining wall and waterproof though now considering a timber frame.  

 

Looking for some advise please how best to connect a timber frame to a retaining dwarf wall and what that make up might look like.  I'm assuming the dwarf wall would need to be block/brick to DPC and then the frame on top though i'm not sure how best to fix the frame to the wall and if the wall would still need to be a cavity to ensure waterproofing, obviously this would add additional depth to that wall.

 

Any advice appreciated, thanks.