My god, sorry, i forgot about you i was busy!
Ok, google gtx 970 Memory Problem or read this ---->
http://wccftech.com/nvidia-geforce-gtx-970-memory-issue-fully-explained/
Iron-Man, very sorry for late reply. Also has 2 sides to it, some are saying they notice no problems & everything is great, others say it's driving them nuts. Have to make own call on this but personally, i would not touch a gtx 970.
If you want better than a gtx 960 and cannot afford a gtx 980 then i'd go with either one of these.
Powercolor Radeon R9 380 4096MB GDDR5 £180
https://www.overclockers.co.uk/showproduct.php?prodid=gx-179-pc&groupid=701&catid=56&subcat=3059
msi radeon r9 390 gaming edition 8192mb gddr5 £260
https://www.overclockers.co.uk/showproduct.php?prodid=gx-289-ms&groupid=701&catid=56&subcat=3059
would also like to say, i5-4690k is no slouch, i have one, it's bloody good. in your shoes, i would get something more like lemin's original spec.
gigabyte z97x-sli - devils canyon core i5 4690k bundle £270
https://www.overclockers.co.uk/showproduct.php?prodid=bu-006-gi
raijintek themis direct contact cpu cooler £20
https://www.overclockers.co.uk/showproduct.php?prodid=hs-001-rt&groupid=701&catid=2330&subcat=2666
kingston hyperx savage red 8gb (2x4gb) ddr3 pc3-19200c11 2400mhz £39
https://www.overclockers.co.uk/showproduct.php?prodid=my-205-ks&groupid=701&catid=8&subcat=2549
crucial bx100 120gb ssd sata 6gbps 7mm solid state drive £47
https://www.overclockers.co.uk/showproduct.php?prodid=hd-054-cr&groupid=701&catid=2104&subcat=1427
western digital caviar blue 1tb sata 6gb/s 64mb cache hdd £42
https://www.overclockers.co.uk/showproduct.php?prodid=hd-366-wd&groupid=701&catid=14&subcat=1279
superflower golden green hx 650w "80 plus gold" power supply £72
https://www.overclockers.co.uk/showproduct.php?prodid=ca-004-sf&groupid=701&catid=123&subcat=2057
samsung sh-224fb/bebe 24x dvd±rw sata rewriter (black) £15
https://www.overclockers.co.uk/showproduct.php?prodid=cd-162-sa
zalman r1 midi tower - black £34
https://www.overclockers.co.uk/zalman-r1-midi-tower-black-ca-088-za.html
That lot is £539. Now for GPU. One of these.....
Powercolor Radeon R9 390 8192MB GDDR5 £260
https://www.overclockers.co.uk/showproduct.php?prodid=GX-178-PC&groupid=701&catid=56&subcat=3059
Gigabyte GeForce GTX 970 WindForce OC 4096MB GDDR5 £260
https://www.overclockers.co.uk/showproduct.php?prodid=GX-149-GI&groupid=701&catid=1914&subcat=1010
Or one of these....
MSI Radeon R9 390X Gaming Edition 8192MB GDDR5 £350
https://www.overclockers.co.uk/showproduct.php?prodid=GX-288-MS&groupid=701&catid=56&subcat=3059
Palit GeForce GTX 980 JetStream 4096MB GDDR5 £380
https://www.overclockers.co.uk/showproduct.php?prodid=GX-015-PL&groupid=701&catid=1914&subcat=1812
That sort of thing would be my idea of a system with or around your budget.
*forgot about windows so i'd go with Win7 £80
https://www.overclockers.co.uk/showproduct.php?prodid=SW-127-MS&groupid=33&catid=1555 Can be upgraded to Win 10 later.