I'm after getting power to my seperate garage, and I have two options:
Run a cable around 30 odd meters of garden wall until it gets to the
garage, or go underneath 3 meters or so of lawn. Either way, it's going
to be exposed to the elements and anything that might be living there,
so I'm presuming armoured cable is a must. I'd rather go underground,
but I have no idea what is required to do so.

Are there any regulations that specify how deep a cable must be buried?
Also, presumably it's a requirement to have that "Warning, you're about
to dig through a bloody big cable" tape over it - is there a
requirement for a certain amount of space between cable and tape?

Also, I really don't fancy digging up and reconcreting the garage or
kitchen floors, so the cable will be leaving the house and entering the
garage through the wall. I'm thinking steel conduit attached to the
wall for the full vertical journey of the cable - is that the right
approach?

Any other questions I've forgot to ask?

Cheers!

Tim