What concerns me here nicsin02 is your basic lack of understanding to Reg's regarding the several areas mentioned above that you never even touched on yourself, as well as a lack of understanding of the function of a 20amp switch.
I assume its and office with computers and alot of them, so to re-enforce what farmelectrics said you have got a functional earthing system and these radials are unlikely to be set up to allow for this or the ring main in that case.
If the socket circuit isn't under the supervision of an instructed person then RCD cover will also be required and i wouldn't be wiring more than 5 or 6 computers to each circuit unless using a SI unit which allows for an increase in this no'.
Basic understanding of regulations which are clearly shown in picture form in the OSG or Reg's to the allowances for spuring of ring circuits seems to be missing from your knowledge which is of great concern.
What are your qualifications and experience as your post and replies are showing a lack of competence, you shouldn't be undertaking this work if your asking the questions you are and also having other major areas of concern been pointed out to you.
Let me make this clear Nicsin02, if you change, alter or make any addition to this circuit/s then you are responsible for its compliance and it will have to meet 17th addition once you do, the high integrity earthing and the need for it is a great concern in my mind as it is a safety issue if not done correctly.
I hope you can take this as valuable advice and not a dig in any way.