No worries. I think newegg just defaulted to the US version since that's where I am. Since you're ordering from your region then you can safely ignore everything I said about delivery and RMA stuff.
Avoid Kinguin. At that price you're not getting a legit license but at best a pulled license from an existing unit. The likelihood of getting a banned key (or getting the key banned at some point) is pretty good. Get a proper license key. You're entire computer runs off that OS so it's worth doing it right.
As for the PSU. The G3 series is a good PSU. It was just overkill for the power draw you have going on. Like I said if it's a good buy at the time of purchase, awesome, if not then go with a lower power unit and put that savings towards something like the OS or GPU, or whatever might benefit from an upgrade. The CS line from Corsair however is not a great unit.
A good starting point for looking at PSUs is this list. It's a bit out of date but it's a good jumping off point.
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html
For a gold rated, non modular. upside is cost, downside is a crap ton of cables to deal with.
https://www.newegg.com/global/uk/Product/Product.aspx?Item=N82E16817151136
For a gold rated, modular. The G3 650 is all of £5 more, so it's not a bad choice.
https://www.newegg.com/global/uk/Product/Product.aspx?item=N82E16817438053
https://www.newegg.com/global/uk/Product/Product.aspx?item=N82E16817438095
For a bronze rated
https://www.newegg.com/global/uk/Product/Product.aspx?item=N82E16817438120
For gold vs bronze, it's about power efficiency. I'd look in to the 80plus rating system to see if you care enough about it. Sometimes Gold vs Bronze can mean a better build quality, but it's entirely dependent on the manufacture of the PSU. Keep in mind, not everyone makes their own PSUs. In fact most don't, so paying attention to who's making your PSU is a good idea. In that tier list I linked, next to the PSU is the manufacture of the actual internals. Johnny Guru does a lot of good reviews so it may be a good place to try learning about PSU's if you care to.
http://www.jonnyguru.com/
The RAM was a good switch up. The i5-8600 can only use up to DDR4-2666 ram so DDR4-3200 is just throwing money away. If you wanted to, for £2 more you could get up to the max speed your CPU supports with:
https://www.newegg.com/global/uk/Product/Product.aspx?Item=N82E16820231892
Your motherboard is a Z series, which means it can support up to something crazy like DDR4-4300. But that speed has to match what your CPU is designed for. Usually people who get Z series motherboards will match it with a K series CPU (i5-8600k in your case) since that allows for the higher memory speeds and overclocking the CPU. Since only the Z series is available now tho, the matchup you're doing makes sense. Just keep in mind the limitations the non K series CPUs have when choosing parts.