I'm about to decorate our dining room, the final step of which will be to
lay some new wooden flooring in the room and hall. Before this is done I
would like to run some trunking from the cupboard under the stairs, where
the CU is, to the back wall of the house so that I can run power to the
garden at some point in the future. It's a straight run from the cupboard
to the outside wall - just over 4 metres. I was planning to fix some
trunking under the floorboards (joists run in the right direction) and drill
a hole through the wall (house c1905, no cavity), covered with a suitable
wallbox, until such a time as I get around to needing to draw cable and get
things wired up. No intention of doing any electrical work at this time.

Are there any special requirements I need to be aware of and what sort of
trunking should I be using?

Thanks in advance.

Mark