Lofting between edge curves of trimmed surfaces?

Hi everyone, I'm just trying to loft between the edge curves of two trimmed surfaces. Basically I wanted to extrude one double curved surface with lots of holes in it to give it some thickness. However to my knowledge you can only extrude a surface in one direction. So i tried offsetting the trimmed surface so i could loft but it was returning a null surface. Finally i offset the surface before i trimmed it and then trimmed it with the same curves as i did with the original and now i just want to loft between the two surfaces to make it a solid form. However when i tried this it doesn't work (I'm guessing because the lists contains both closed and open curves). Please help me! I'm pretty new to grasshopper. It should make more sense once you see the files.

Cheers,

Rob