The specs for that game are rather daunting!
The recommended graphics card alone costs £568 for the nVidia model
http://tinyurl.com/js2bbgg
but the Radeon one is only £180
http://tinyurl.com/z9k5xlu
The recommended Intel processor costs £300
http://tinyurl.com/hca4gnl
but the AMD one is only £135
http://tinyurl.com/zqk5zrl
Looking at that last link shows that you can get a motherboard and 16Gb of RAM to go with that processor for a grand total of £310. Adding on the Radeon graphics card takes that up to £490. Then you'll need a reasonably hefty power unit, at least one optical drive, a case (with USB ports, etc), some cables and a cooling system. (You might need a water cooling system. They start from around £180). You'll also need an operating system. (Windows 10 Home costs £100)
Lastly, you'll need someone to put it all together for you. (The best way to get a gaming machine to meet your requirements is to have it custom-built).
So you're looking at around £1000 for the components, plus the costs of construction. You'd need to shop around for that. Putting the components together only takes a few hours (or a little longer if water-cooling loops need to be installed) but installing the operating system and drivers adds further time on, as does final testing.