Thank you all for your advice - it's all been very useful. I've made some final changes and I'm a bit over budget but its not a big deal. I decided to get some extra case fans for the rear as the case doesn't seem to come with a rear fan on it's own but I'm not sure whether that's necessary (some feedback on that would be great). Here's the updated build.
PCPartPicker part list:
https://uk.pcpartpicker.com/list/HZ6B3b
Price breakdown by merchant:
https://uk.pcpartpicker.com/list/HZ6B3b/by_merchant/
CPU: Intel - Core i5-8400 2.8 GHz 6-Core Processor (£175.99 @ Aria PC)
Motherboard: MSI - B360-A PRO ATX LGA1151 Motherboard (£81.23 @ Box Limited)
Memory: Corsair - Vengeance LPX 16 GB (2 x 8 GB) DDR4-3000 Memory (£102.78 @ Aria PC)
Storage: Crucial - MX500 250 GB 2.5" Solid State Drive (£42.50 @ Aria PC)
Storage: Western Digital - Caviar Blue 1 TB 3.5" 7200RPM Internal Hard Drive (£37.59 @ Aria PC)
Video Card: Asus - GeForce GTX 1070 8 GB Dual Series Video Card (£339.98 @ Ebuyer)
Case: Fractal Design - Focus G (White) ATX Mid Tower Case (£50.44 @ More Computers)
Power Supply: EVGA - B3 550 W 80+ Bronze Certified Fully-Modular ATX Power Supply (£63.98 @ Ebuyer)
Case Fan: Corsair - Air Series White 2 pack 52.19 CFM 120mm Fan (£22.89 @ CCL Computers)
Total: £917.38
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-02-21 16:08 GMT+0000