"I get the distinct impression that the OP has a figure in his head, but no real reasoning why. While 2 grand obviously gets you a better bike than one for half the price, if all you're doing is social riding, you don't need it. That's sensible advice.
I've given what I think is a really good option in a CAAD12 (possibly an even better frame than CF at that price point), but you can spend less than that and get a very nice bike that'll fill the OP's requirements and then some. Apologies if that offended you in some way."
Lets face it, (and I could be wrong) but most of us dont need half the stuff we have and if he really wants just a bike for social riding a triban will do the job as well as anything else. He doesn't need 105, or hydraulics etc etc, as the new tiagra is pretty good and bb7s are not bad brakes, but he wants them. If you ditch the carbon option, the best at that price with decent wheels is probably the planet X london road.
However at the £2k option, the ones I would look at other than the Defy and Roubaix are the cannondale synapase and trek domane.
Either way all of them should be dropping in price soon.