Top of the list is this Pinnacle which I need to try size wise (5’9+3/4!). There’s also the frame only option of the same bike so I could do a custom build for similar cash and a few spec tweaks.

I’d like;

Drop bars and discs.
Carbon fork
105 groupset
Sub 10kg

Room for 32mm tyres probably sufficient (aware the above won’t do guards and 32’s easily/at all). I am realistically not taking it off road properly, an Arkose is as tough as I need and in the mix.

I’m open to second hand but not spotted anything recently- Giant Revolts, Whytes and Merida on the radar. Any other bargains out there?

This in no way fulfills your requirements, but I am lusting after this for a commuter:
Belt drive!

For me personally I’d get this frame and build it up.

http://www.leisurelakesbikes.com/p/17488/whyte-sussex-racing-road-bike-2015

Any others?

Charge Grater 3 or they do cheaper ones with upgrade possibilities.

Don’t overlook sora for a commuter, it’s bomb-proof, and cheap.

Go flat bar and get the 1×10 Whyte Shoreditch

^^^ this and spend the savings on a CX wheelset.