Ah, yes, I read about the multi-zoning as well but I forgot about that.

As a committed diy-er all my previous systems were multi-zone but as the
first almost all TRV system I thought why bother. It's easy to incorporate
fortunately. I think the property will count as big.

So - provided my system design and controls ensure a water path at all times
that the boiler is firing, which I would have done anyway without really
thinking it was anything special, I don't need a bypass, automatic or
otherwise?