Balanced your build to fit your budget (based on components showing on PCPartPicker):
https://uk.pcpartpicker.com/list/gf9nhq - total £598.44
The motherboard I've picked is virtually identical to the Tomahawk / Arctic boards, just with a different UEFI and apparently different capacitors. I have an Arctic board and I can't yet run my 3200MHz RAM beyond 2133MHz stabily with AGESA 1.0.0.4, so I've reduced your RAM to 2666MHz, which has a great price/performance ratio for a mainstream build.
Going from R5 1400 to 1500X isn't really worth it if you're okay with playing the silicon lottery and overclocking. (My R7 1700 isn't a golden sample, but has gone up from 3GHz to 3.6GHz with a bump to 1.2125V.)
If you're okay to drop down your RAM to 2x4GiB (which leaves you the option to upgrade later), you have more money to spend on graphics card (ideally RX 570 if it comes down to RX 470 pricing). Unless you're planning to get a 225-300W graphics card, you simply don't need a beefier PSU.
Alternatively, from a future-proofing point-of-view, you'd be better-placed spending money on an R5 1600. Those extra two cores and four threads may not be useful to you now, but this is where the current mainstream gamer market will likely start to move to over the next few years.
At the end of the day, you must do you. I offer my advice without expectation of you taking it or thinking ill of you if you don't. I wish you good fortune whatever you decide