Shed / Workshop base advice

[Excalibur88]

Need advice please gents.

The garden has a fairly significant slope towards the house (more so than it appears in the photos).

The excavated area in the photos is for a wooden shed/workshop. I dug the area out last autumn by hand - massively underestimated how much earth needed to be removed to get it fairly level (never again!).

I plan on building a small retaining wall along the back edge with drainage although it's only 230cm long x 60cm tall at present so is drainage to relieve hydrostatic pressure required?

I also plan on slabbing the rest of the area so it is level with the existing slabs and moving/reusing the existing drainage. Two issues I can see:

1. To get the correct level of hardcore, sand, slab bedding material etc I need to take a few more inches out the entire area but I don't feel I can go lower along the boundary because the concrete holding the post in is already partially exposed.

2. Would I need drainage similar to the existing along the boundary?

I'm not a builder by any stretch of the imagination so apologies for the dumb questions.

Thanks in advance

 

[Alec_t]

To get the correct level of hardcore, sand, slab bedding material etc I need to take a few more inches out the entire area but I don't feel I can go lower along the boundary because the concrete holding the post in is already partially exposed.

Would it be so bad if the shed base were above the level of the existing slabs? Might even be an advantage to prevent water running across the shed floor.