Hey, welcome to TR.
The Corsair 500W unit you've picked is fine - you can spend more but it'll be more than adequate and it's a reasonable price. Graphics cards that "require a 500W power supply" are just the manufacturer covering their own arse. Cheap 350W supplies probably can't even reach 350W so they are just overcompensating. That 500W Corsair will be able to provide a constant, solid 500W without problems.
The build looks pretty sound - I have two recommendations:
Firstly, the 560Ti is old and not particularly competetive anymore. For £185 you can get much more for your money, such as
this £150 HD7850. For significantly less money it will be anything from 10% to 75% quicker - depending on the game.
From your description though, that's overkill; Something quieter and cheaper will be more than enough for you at the moment. How about this
£90 HD7770 which will run even the latest games at high settings on a 1080p screen.
Secondly, if you value a responsive system I would suggest going with the HD7770 to save almost £100, and using that money to buy a solid-state disk. The hot favourite at the moment is the Samsung 830, though
this Kingston is a good deal at the moment. You would install Windows, your programs, and maybe a few of your favourite games on it, then keep everything else on the 1TB drive. If you've not used a computer with a solid state disk yet, then you should know that it's pretty amazing at making everything feel snappy and responsive.