Ok, easy peasy. Keep the normal CH and HW seperate from the UFH, programmer, room stat and cylinder stat as normal, then your UFH will have it's own controls. Three core and earth from the UFH controls to each programmable room stat, the pump and zone valve as well as the actuators will wire into these controls. You'll need a T+E from the UFH controls and from the wiring center to the boiler for your switched line conductors. If the controls for the central heating system are local to the boiler then take a feed for the boiler, UFH controls and wiring center for the normal heating controls from one spur nearby. If controls are not local to boiler, you'll need relays at the boiler so your boiler can have it's own feed. The UFH controls should have labelled terminals so are pretty straight forward for anyone to wire.