Installing additional sockets on spur

[PrenticeBoyofDerry]

Looking at the CU my 3 circuits (shower/mains/lights) protected by a trip are single connections from the CU so would all be the radial design, the mains being 2.5mm cable.
So I could keep the existing cabling and put a individual fuse box on the existing 'feed' socket or remove the existing socket and extend (using a junction box) the cabling for this then redundant socket to the two new twin sockets that I want to install.
That would be fine and dandy wouldn't it so would be back to being the simple project I originally anticipated it to be.

If it is a radial on 2.5mm cable, then the expected fuse/mcb rating must be no greater than 27A. So a MCB of 25A or 20A should be in place.
Again radial circuits don't require multiple spurs to be fused via a fused connection unit (FCU), but there are requirements for cables that are not mechanically protected and buried less than 50mm within walls to be RCD protected, and your additional sockets will also require 30mA RCD protection regardless of that.
So you would need to consider the best way forward to conform to this, you could install RCD protected FCUs at each point where the feed for additional sockets are going to be taken or install a type tested RCBO for the whole circuit. An RCD/FCU could well cost the same as a RCBO, so if you required more than one RCD/FCU, an RCBO would be more cost effective.
Links to both below, bear in mind your make of board is likely to different to that, that I have linked and the RCBO should be type tested to the make of board.
http://www.tlc-direct.co.uk/Products/CM4904.html
http://www.tlc-direct.co.uk/Products/CM92003SP.html
Also take a look at permitted safe routes in Wiki
//www.diynot.com/wiki/electrics:installation_techniques