I'm not sure if anyone suggested this before, because I did not bother to look at all the comments after the first page, so I'll just suggest that you get a better graphics card for cheaper. I saw that someone suggested a gtx 750Ti, which is weak compared to the one you have in mind, but there is the gtx 770, which is considerably higher for a cheaper price.
www.videocardbenchmark.net/high_end_gpus.html
As you can see in the above link, it's performance surpasses the one you plan to order. If you plan to order online, I'm sure that I'll be able to get you a few websites that will ship to the UK for a good price.
Pm me on steam if you want, I might be able to help you a lot more, bet your specs seem good, although I would suggest going with at least 700-750 W PSU, since a little overkill in PSU's is almost always good.
P.S. I'm building a gaming pc too, so I've done lots of research on the topic. ( No need for an SSD now, you can get one later.)
Ignore, just realized you got a gtx 990
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