^ Good build but 240GB is way too little and for that budget 1 TB HDD will do for now. Reduce the 1300x to 1200 which can OC to match the 1300x.
PCPartPicker part list:
https://uk.pcpartpicker.com/list/G7PNQZ
Price breakdown by merchant: https://uk.pcpartpicker.com/list/G7PNQZ/by_merchant/
CPU: AMD - Ryzen 3 1200 3.1GHz Quad-Core Processor (£71.94 @ Aria PC)
Motherboard: MSI - B350 PC MATE ATX AM4 Motherboard (£69.99 @ Ebuyer)
Memory: Team - Vulcan 8GB (2 x 4GB) DDR4-3000 Memory (£85.99 @ Overclockers.co.uk)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£35.99 @ Aria PC)
Video Card: Zotac - GeForce GTX 1050 Ti 4GB Mini Video Card (£143.94 @ Aria PC)
Case: Cooler Master - MasterBox Lite 5 ATX Mid Tower Case (£40.02 @ YoYoTech)
Power Supply: Corsair - CSM 550W 80+ Gold Certified Semi-Modular ATX Power Supply (£74.95 @ Box Limited)
Operating System: Microsoft - Windows 10 Home OEM 64-bit (£82.72 @ More Computers)
Total: £605.54
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-04-02 03:43 BST+0100
5 over due to OS, otherwise cheaper and with a good quality PSU.