Consumer Unit layout

[Qedelec]

Best to avoid junction boxes where ever possible.
If you can, incorporate all sockets in the ring by drawing in new cable.

Consider adding a separate ring for the office and connect to the non-protected side of the RCD. Again earth leakage can be a problem with IT kit, especially those pesky surge protectors.

 

[Rob_Quads]

Hmm probably easier then just to leave the main ring alone and have the office on its own. Upstairs other than the office there is not going to be much using power

 

[Qedelec]

Rob
I am in the process of updating my house and as most offices seem to need copious amounts of sockets but very little demand, I am adding dado trunking to which additional sockets can be added at any time. It also can incorporate the phone line and looks professional. This trunking is on a separate ring non-RCD protected.

 

[ban-all-sheds]

It can go on either side, although if it has a socket it should be protected by the RCD as its possible to connect an outdoors appliance.

The regs require it to be "reasonably expected" to supply portable equipment outdoors for it to need RCD, not just "possible".