Is this a good build?

Solution
Not really. PSU is not good at all, cooler is not enough for OC, and RAM is too slow and only single channel.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core OEM/Tray Processor (£219.54 @ Aria PC)
CPU Cooler: be quiet! - Dark Rock 3 67.8 CFM Fluid Dynamic Bearing CPU Cooler (£56.50 @ Aria PC)
Motherboard: MSI - Z370 GAMING PRO CARBON ATX LGA1151 Motherboard (£136.76 @ Amazon UK)
Memory: G.Skill - Ripjaws 4 Series 8GB (2 x 4GB) DDR4-3000 Memory (£90.98 @ Amazon UK)
Storage: Kingston - SSDNow UV400 120GB 2.5" Solid State Drive (£44.95 @ Amazon UK)
Storage: Western Digital - Caviar Blue...
Not really. PSU is not good at all, cooler is not enough for OC, and RAM is too slow and only single channel.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core OEM/Tray Processor (£219.54 @ Aria PC)
CPU Cooler: be quiet! - Dark Rock 3 67.8 CFM Fluid Dynamic Bearing CPU Cooler (£56.50 @ Aria PC)
Motherboard: MSI - Z370 GAMING PRO CARBON ATX LGA1151 Motherboard (£136.76 @ Amazon UK)
Memory: G.Skill - Ripjaws 4 Series 8GB (2 x 4GB) DDR4-3000 Memory (£90.98 @ Amazon UK)
Storage: Kingston - SSDNow UV400 120GB 2.5" Solid State Drive (£44.95 @ Amazon UK)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£36.59 @ Aria PC)
Video Card: NVIDIA - GeForce GTX 1060 6GB 6GB Founders Edition Video Card (£279.99)
Case: NZXT - S340 Elite (Black) ATX Mid Tower Case (£73.52 @ Aria PC)
Power Supply: Corsair - TXM Gold 550W 80+ Gold Certified Semi-Modular ATX Power Supply (£63.17 @ Ebuyer)
Total: £1002.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-01-20 20:38 GMT+0000

Not a fan of 120 GB SSD either, but left that to you - personally I would just ditch it until you can afford 240 GB one.
 
Solution