Struggling to choose a CPU since the i5-3570k and 4670k are just out of my price range and I'm not sure whether I should save up for longer and get those or get an fx 6300 or fx 8320 / 8350. I was thinking about something along these lines but maybe with a better graphics card. http://uk.pcpartpicker.com/p/2HoGf
Will I notice the difference between those cpu's both in and out of games?
That is a decent build for most things, should play most current games on high/max settings at 1080p maybe not newer games in the coming years. If you need high productivity or want max settings in games for the future then the 4670k is a great CPU, but I think you'll be fine unless you have some specific needs that could really use more CPU horsepower. If you wanted a more powerful GPU while staying within your listed budget, try this Asus gtx760 http://uk.pcpartpicker.com/part/asus-video-card-gtx760dc2oc2gd5
Like the build in the OP. I like the suggested 760.
I think it would be beneficial to include a much more capable wifi adaptor. Wifi isn't ideal, and you should probably try to compensate with a higher theoretical throughput.