it is that simple. behind the knockout on the boiler there will be wires waiting for you in a connector block. the L & N power the clock motor & the other two are the live to the heating in & out. there will be a simple diagram with the clock.
i would recommend the simpler electro mechanical model.
http://www.heatingcontrolsonline.co.uk/mechanical-timer-for-combi-boilers-p-351.html
& no its not really ok to resurrect the thread.
Thanks very much, I'll get one and have a go.
Why would you recommend the mech version over the digital? the only reason I would prefer the digital version is that we get up early in the week (5ish) and would want the heating on early on these days, but not at w'ends.
bit late over the resurrecting.....