OP
James Palmer
Just read the OP again and your old boiler had an internal programmer so you are going to have to get a two channel programmer. Do you have a room thermostat and cylinder thermostat?
I will get a 2 channel programmer - would you recommend a particular make - in terms of reliability and ease of use, I also need a 1 channel for the immersion?
There are room and cylinder thermostats which wire into this grundfos box.