Morning
The arctic 360mm cooler is best bang for buck so to speak, as the rad is thicker than standard rads, so more cooling effect as more surface area for fins etc. Comes with 6 year warranty so should last the duration of this build also. Truthfully, most 360 rads will do the trick though, just get one with a good warranty. If it's performance and price and not hung up on looks, then the arctic is the one
Separately, been looking at the GTX 1660 Storm you have in there. It's not that much faster than the 1050ti you have at the moment and doubt it'll make much of and impact, the 12700k being the heavy hitter of the combo. If you're not happy you can just buy the gpu later and swap them. Simple to do, and wont impact OCuk ability to build as the 12700k has inbuild graphics so can still test system
One thing to remember for when OCuk build, you'll either have to pay for Win 10/11 license from them, or load it on when it get delivered, unless you can transfer your existing code (you'll have to ask them about that), or maybe they can load it up, and you put in code when it's delivered
regarding boards, I generally look at the vrm performance as want a board that runs cool so like hardware unbox for reviews, and gamernexus to a degree..and the gigabyte boards performed the worst for that in reviews below. The board you have selected had 9usb, 1 usb-c, 2.5 lan, hdmi and dp port, no wifi for £250 and runs at 60 degrees with 12700k...thats 2 degrees warmer than the MSI Pro Z690-A board which cost £169, which has 7usb, 1 usb-c, 2.5 lan, hdmi and DP port, so you're basically paying £80 for an extra 2 usb ports( you can buy a pci 4 usb port card for £12 if you need more)...if you want to pay that much I'd go Tomahawk, at least it has wifi 6 on top and a bios flashback button, and runs 7 degrees cooler on top as better vrm..having the wifi will prob add some value when selling in future too.
Going B660, the B660 Tomahawk has 8 usb, 1 usbc, wifi6, hdmi, dp port lan port for £189 also, and best performance of all b660 boards....all the boards mentioned have 6 sata ports too
so just be 100% on board...they'll all do the job, but as said, that gigabyte board is expensive for what you get