I think that Raleigh Strada looks just fine. My primary bike (a Trek in the US) has a very similar drivetrain to that Strada, and it works a treat. The derailleur on Strata's website is noted only as "Acera", but it's probably an M360 or similar and it works well. The shifters will work fine, and it has hydraulic disc brakes. My bike has a Suntour NEX fork, and mine doesn't even have a lockout, and I enjoy it on mine. I have probably 500 miles on mine so far and the components have served me very well, and everything still works like it did 500 miles ago.

Regarding suspension seat posts, my Trek has one, and I actually don't think it works all that well. I may replace it with a rigid seat post, but will leave it for now. It doesn't operate nearly as smooth as the suspension fork, and it seems like it's pretty much stuck in one position until you REALLY jar it, then it'll give suddenly. I think the concept has merit, but mine doesn't work all that well. Otherwise, that Saracen Cross-2 looks fine as well. Similar drivetrain to the Strada; very functional.

The Whyte Fairfield looks interesting. It has a similar drivetrain spec as the other bikes. It has a rigid fork and rim brakes, and it appears to sell for a similar price. Maybe there is something to their claims of unique frame design, I don't know. It's weird how they mount the rear rim brake UNDER the seat stays, which moves the noodle to the right side of the bike. It also has decent-looking 42mm tires, which I think are wider than the other choices (which I generally prefer).

I'm not up on the value of a British Pound, so I don't know if those are good or bad prices, but the bikes themselves look like decent choices. Not high-line bikes, but not bottom-basement bikes from a big box store, either.