Electrical entry point. How and where?

Hi all, I've almost finished pouring the strip foundations for my studio. So I'll very soon be pouring the slab. This is the link to my design thread: viewtopic.php?f=1&t=21057&start=15 I just wanted to check whether it's preferable to install the electrical inlet to the "garage" consumer unit in the slab before it's poured or through the walls once constructed. I'm leaning towards in the slab, but wanted to check whether this is practical? Would this require SWA (Steel Wire Armoured) cable? Thanks, Dan