Hi Pal,
Here is an idea of what is possible with your budget in the UK, I am from here too. A couple of things that would help, is a monitor required? is a case required?
Other than that, I have put together a Ryzen 2600 6 core 12 thread PC that is great at productivity including streaming and editing and will play games fairly well including triple AAA titles but at 1080P.
Below is just an idea on whats possible and you can make changes to drop the price somewhat by choosing slightly different parts to save more money..
PCPartPicker part list:
https://uk.pcpartpicker.com/list/Wh4LnH
Price breakdown by merchant: https://uk.pcpartpicker.com/list/Wh4LnH/by_merchant/
CPU: AMD - Ryzen 5 2600 3.4 GHz 6-Core Processor (£145.99 @ Aria PC)
Motherboard: Gigabyte - B450M DS3H Micro ATX AM4 Motherboard (£65.80 @ Box Limited)
Memory: Team - Vulcan 16 GB (2 x 8 GB) DDR4-3000 Memory (£108.65 @ Overclockers.co.uk)
Storage: Kingston - A400 240 GB 2.5" Solid State Drive (£29.99 @ Amazon UK)
Storage: Western Digital - Caviar Blue 1 TB 3.5" 7200RPM Internal Hard Drive (£34.79 @ Aria PC)
Video Card: Asus - GeForce GTX 1050 Ti 4 GB Phoenix Video Card (£148.98 @ Ebuyer)
Power Supply: be quiet! - Pure Power 11 CM 500 W 80+ Gold Certified Semi-Modular ATX Power Supply (£64.58 @ CCL Computers)
Total: £598.78
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-12-10 11:13 GMT+0000
Windows 10 can be had on offer for as little as $12.30 via this link:
https://www.tweaktown.com/news/64075/deals-windows-10-pro-12-26-more/index.html