Is this build enough to play latest games on med/high settings?

Here is the list:

PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor (£146.99 @ Aria PC)
Motherboard: Gigabyte - B360M H Micro ATX LGA1151 Motherboard (£63.97 @ Scan.co.uk)
Memory: Team - Vulcan 16GB (2 x 8GB) DDR4-2400 Memory (£139.99 @ Overclockers.co.uk)
Storage: SanDisk - SSD PLUS 240GB 2.5" Solid State Drive (£59.94 @ Amazon UK)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£35.99 @ Aria PC)
Video Card: MSI - GeForce GTX 980 4GB Twin Frozr Video Card
Power Supply: SeaSonic - FOCUS Plus Gold 550W 80+ Gold Certified Fully-Modular ATX Power Supply (£65.50 @ Amazon UK)
Optical Drive: Lite-On - iHAS124-14 DVD/CD Writer (£10.50 @ Aria PC)
Total: £522.88
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-04-10 12:40 BST+0100

£30 more but is huge improvement over yours list because it comes with i5-8400 instead of old gen i5-7400. I included 16GB DDR4 RAM instead of 8GB kit. I also included 240GB SSD instead of 128GB SSD. All are good and high quality components enough to support your needs.
 
Solution
Are you buying everything used?or just te graphics card.

I5 7xxx series are not recommended anymore as new coffeelake 8100 is essentially the same with support on the most recent platform for upgrade easier upgrade path.

8100 sits between 7400-7500 interns of performance, and it’s a lot cheaper than the i5 7xxx.

If you don’t overclock and just want a decent system to run for the next few years, 8400 with H310 board offers the best performance to value, it’s the replacement of 7400 but with two extra cores.