Taking a spur for outside socket - want to check it's safe

[Codger69]

I want to create an outside socket for garden use but one of it's uses will be running a Lay-Z-Spa over the summer which run at just over 2000 watts when heating with possible short bursts of 2850W if it happens that the pump, air bubbles and heater are all on (minutes at a time). The Lay-Z-Spa runs off a 13 amp plug and has an RCD built in to it's cable.

The obvious choice is one the kitchen sockets. There are two that are suitably placed.
The one on the left has only one cable running into it so I'm concerned that is already a spur.
The other, to the right is wired as per attached photo. it is a two-gang socket.

In case it isn't clear, there is an unbroken cable running across the back of the socket and one in either side.

1. Is this a good idea at all?
2. Is this a good socket to use?
3. If so can I just attach a cable to one appropriate terminals of the socket?

Many thanks

 

[securespark]

It's difficult to say without testing those two cable ends, but it certainly could be a ring final.

What size MCB or RCBO protects that circuit?

 

[Codger69]

I have a multi-meter if required.

It's controlled by an MCB which is marked "downstairs sockets" and that is a 32A (Hager B32 MT132 450132)