I reckon you get a lot for your money with the wsd Giant SCR range. I've got the 1.5 which is the top of the range of 3. Retails at £650.
Things to consider are:
triple or compact - rings. You have lower gears with a triple. If you are very strong in the legs perhaps a compact, but personally I think a triple is def better esp in Peaks and def to start with, if not for ever! Worth trying them both I guess if you can.
Gears spec - tiagra is the better spec and operates slightly different to the lower spec Sora. Try them both.
That's all I know about specs on road bikes 
The main thing to consider is the size I guess.(well, apart from the colour of course!) Oh, and the wsd have smaller reach on the brakes. These aren't adjustable like they are on mtb's.
Enjoy.... Looking forward to our roadie outings (they have mandatory tea shop stops!!) 