OK, so we can see that the sockets in your house are protected by a 30mA RCD. This is good news as, aside from the fact that it is required for the underfloor heating, it will also mean you don't need to worry about meeting the requirements for mechanical protection/burial depth that apply to non-RCD protected circuits under the 17th Ed.
Looks as if you have a problem here with regard to safe zones, as once the plasterboard is back in place there will be no evidence as to the presence of the cables in that wall. If the stud wall is <=100mm then the placement of an electrical accessory vertically inline with the cables on either side of the wall may be sufficient to create a 'safe zone' for the cables, subject to certain conditions (follow link to the WiKi).
The alternatives are for the cable to be buried at a depth of >50mm (although it's hard to see how you'd manage that from either side, the wall doesn't look deep enough) or provide earthed mechanical protection by way of SWA cable/Pyro/earthed metal conduit, none of which are particularly practical in your case.
If you can confirm this socket is part of the ring final then yes, you can take a spur from it.
But then, when i had a brew and some brain food (Sausage & Egg butty)
i had another look at the set up and if you follow the level to the end,
directly opposite to that in the other room is a 1 gang socket, same hight
as end of level. This i thought might be perfect as all i would need to do
is cut more away of the plasterboard to expose the back of the socket
and spur off from this, though the battens and up the conduit with the
cold cables. Is this my best option or not chaps or am i barking up the
wrong tree ???
Again, if said socket if part of the ring final then you may spur from it. However, there will only be a horizontal safe zone extending from the existing socket, so you can't just run the cable horizontally and then take a 90 degree bend into the vertical and up into the loft without an accessory on the wall to create a vertical safe zone.