3 way valves for hot water to showers/sinks

[unclebob1]

Good Morning All,
Just planning my plumbing for house renovation, i will be looking to have the following hot water outlets:

Bathroom1: Sink + Shower + Bath (Either shower or bath but never together).
Bathroom 2: Sink + Shower
Kitchen: Sink.

I'm currently thinking at getting a Combi boiler + DHWT, with piping such that the showers + bath run from the DHWT, and the sinks are fed from combi.

What i would like however is the ability to switch each outlet's source - from DHWT to combi or the other way round, as well as isolate off each outlet for maintenance.

So ideally im looking for a 3 way isolator valve, but anything i look for online is from ebay/aliexpress or electric/motorised.

Does such a valve exist from real plumbers merchants/suppliers or is a fleebay special and instead i should look to have an arrangement of two/three single isolators in a t config?

boiler/tank still to be specified by heating engineer, but looking to do the water side in preparation for change over (Suggestions are welcome - ground floor will be wet UFH, 1st floor will be 3 rads running of manifold. each room/zone will be individually controlled. HW requirements as above).

 

[picasso]

Absolute overkill for a domestic property, if you want to go for combi and unvented cylinder I would have one bathroom on the combi (basin and shower) and the basin/shower/bath/kitchen sink on the unvented cylinder, the combi can be isolated by simply turning the water supply off under the boiler and you could put the cylinder on a manifold if you wanted to control/isolate each outlet.