Wiring up heating controls

I need to wire up my underfloor heating controls as per the link below:

http://www.underfloorheatingdiy.co.uk/wiring_boiler.html

I just have a few questions i hope someone can help me with.

1)I have a double socket (part of the ring main) near where the heating controls are going, can i use this socket to spur off for my Live, Neutral and Earch via a FCU?

2)Can i use 2.5 twin and earth cable to connect the switch line from my boiler to my controls? Or do i need a particular type/colour?

3) Would it be best to use a junction box or chocolate block (then blanked off)? What Amp chocolate block would be best suited?

If this is interconnected to the boiler circuits then i suggest you run it from the isolation switch for the boiler. Then u have a single point to switch off all the heating.

If you dont do this then some of the heating will still be live when you switch off one part - not good.

The fuse in the boiler isolator will dictate how big the wire can be. Thats what fuses are for.(I assume you'll follow above).
If the boiler fuse is 3 or 5 amp then you'll be OK with 1.5mm cable.

Thank you for your help that makes perfect sense, the only reason i thought of spurring off was so i didnt have to run a cable down from the boiler but i have to run one down for the switch line anyway.

u can run 3core & earth to do what u need.