Here's a reasonable idea of low/mid-budget, but pretty decent gaming -
https://uk.pcpartpicker.com/list/42NWjy
Presumably you'll be gaming on a 1080p monitor?
Still got a case, operating system, monitor, mouse, keyboard and speakers / headset to add to that. Guessed you may have some or any of these already, so left them out. You might also consider additional storage at the back of the 480GB suggested. I paid no attention to aesthetics when choosing the parts (that tends to cost extra
)
The vendors listed are just 'best price' at the moment. It might be better to see the 'prices by merchant' (top right of screen) for grouping them. Also be aware that prices listed aren't always 100%. Amazon's prices can be iffy, especially if the parts are coming from the US (import taxes not listed in PC Partpicker). Also, some Amazon prices are Prime-only options. My general 'trusted vendors' are:
Ebuyer
CCL
Overclockers
Aria
Amazon (from them; not from some other Amazon seller, although at a pinch, I would take a 'fulfilled by Amazon' option).
Also look out for occasional bargains on skinflint.co.uk (via vendors you trust, of course)
The CPU is a decent 6-core, with plenty of potential for mid-range gaming. The stock cooler might not be fantastic, but it'll do for budget needs.
16GB of RAM at that price today isn't bad at all. Ryzen CPUs can run at 2933, but 2666 will work too.
The Adata 480GB M.2 drive is very competitively priced for the GBs onboard, and said drive is pretty high on bench tests.
A GTX 1060 6GB is more than adequate for 1080p gaming for most games at present. The Asus model there tends to get decent reviews.
An 80+ Bronze, fully modular PSU. Semi and non-modular ones are not all that cheaper. I recommend Seasonic and Corsair.
If you want 1440p gaming, you'll ideally want a minimum of a GTX 1070 (£400-ish*), but a 1060 will work. You'll just have to lower some settings, depending on the game. For 4K gaming, you're talking minimum of GTX 1080, and ideally 1080 Ti or the new RTX cards (guessing your budget isn't looking at all this though, but thought it fair to point it all out).
* Prices and performance of 1070 Ti cards almost make 1070 cards pointless
Edit: Forgot to add. Ebuyer's 'free delivery' is Yodel. Used them recently. Was really, really worried. They turned up 30 mins late on one drop, and were fine for another. Suggest you're 'in' if using them.