What finishing kit/how much to spend?

I think I'm set on the wheels to keep costs down went with the DT Swiss 240 hub I was considering the 180 hub, that'll account for some of the cost difference to the hunts. Just a question of 700c or now leaning more to 650b.

Which Deda models ? I was also looking at Richey venturemax but not sure if like the looks of how the levers sit.
I'm now also looking at 3T finishing kit as like the look of the Explora ( and Open u.p ) full bike. The 3T handlebar for gravel/adventure use is £300 which although more then I wanted to spend but could live with but the matching ltd stem is also £300 or their alloy one is £90 not sure if could mix n match. The 3T seat post is £250 ish iirc and can be set up with either 0 or set back.
If went 650b then might go wtb tires and seat?

Yeah so my thinking is, it's the only one bike to rule em all/do everything, I can justify the cost as main purpose will be commuting and will therefore pay for itself in the long run, it also guarantees daily use and not just sat in shed. I also want to do more off road trail riding with the growing family wife, 2 boys aged 4 and 10. As well as weekly social ride instead of gym spinning class. I used to commute 5 mile each way daily until changing jobs which prevented this, I'm changing jobs again and gives me about 10 mile each way.

As main focus is commute that could change and mainly on tow path cycle network and parks the build is focused on this, so mud guards, racks and dynamo are a must for me over weight. I can't justify buying two mediocre bikes, one for commute and one for club runs and sods law I'd be on the wrong bike at some point anyway so rather put all eggs in one basket, with a frameset that is adaptable and versatile such as 650b or 700c wheels, talking of which, I really can't decide which size to go for out the two or what tire width??

Having done a test run of the new commute the other day, meeting a guy with a puncture and seeing how exposed it is, it'll be slippery and dark in winter, so again, thinking tubeless with sealant as doing both road and off road I really can't decide wheel size and the dymano light be Supernova E3 Triple.

No the wheels whatever size be hand built Son Delux and DT Swiss 240 hubs on carbon 30mm rims CX spokes about £1500 handbuilt.

I've attached the spec contenders so far, any thoughts, comments suggestions welcome, I agree I need to see/try/feel as many different ones as possible but hard finding local shops with a good selection particularly when spoiled for choice. I also agree and will have a bike fit for measurements and sizing;
Thanks Andy