Lots of manifolds available these days. They're a much of a much, the key part is the blending valve and the pump. There doesn't seem to be any control on that one, unless the pump is the control and is what that wiring may be for??
Reliance are big in the UFH components world, alongside the bigger guys Wavin(HEP)/JG/Polypipe ..... Grundfos are always good in the pump world.
Do buy branded though, don't guy generic as there is then a level of future proofing. Make sure there are service kits available, always a good idea to buy one at the time and store it for later.