UFH underlay for one side of open plan kitchen/diner

Hi, there’s a lot going on here and if I’m honest you really need to get as much information from appropriate manufacturers before deciding anything as a floating engineered wood floor will expand and retract more then a fully stuck floor, adding underfloor heating is one thing to be carful about you need correct underlay so you don’t loose any heat, don’t ever install kitchen units on top of floor if floating. I would also suggest a break between floors. Check with manufactures and don’t ignore there recommendations, I’ve seen many jobs where customers have spent thousands to be installed without knowledge for the materials being used.

Being a perfectionist even 1mm will be felt by your feet at the transition of the flooring and the human eye picks up all irregularities by nature. I would aim to get equal thickness underlays to avoid a visual transition.