From my nice new kitchen I want to run a spur to a 240v fountain in the
garden.

First of all, can I do this? I really don't want to run the cable back
to the CU, which would be very hard due to the topography of the house.
I'm hoping I can use an RCD-protected FCU to spur-off from one of the
kitchen rings (there are two) and run it through the kitchen wall from
that.

If this is within the regs I presume I should be using SWA cable to get
to the fountain. In which case what would be the appropriate junction
box for joining the SWA to the spur within the house? Is there any FAQ
that covers working with SWA?

In fact is SWA cable necessary? The cable will be clipped to the side
of the building, it will go through a conduit which is already burried
under the patio, and it will emerge by another wall which it will also
be clipped to until it reaches the fountain.

Many thanks,

Martin