Hi, yes the PSU will cope comfortably
If you're not over-clocking then you're probably around 250w full load at the moment, even with another GTX670 I think you'll be around 400w, certainly under 500w. Seasonic PSUs are very good quality and can output their full rated loads continuously, unlike very cheap PSU that might manage half their rated load!
230v mains voltage results in higher efficiency, slightly, then 120v found in US/Canada etc, this helps the PSU deliver it's power as it produces less waste heat inside itself.
I can run my PC off an old S12-II 330w PSU, my 2600k is more power consuming than your newer 3570k and my GTX560Ti is also very similar power consumption to the newer GTX670 so your PSU with twice the capacity will be just fine, even if you over-clock as hard as you can.