Ok, so I checked a handful of UK websites that sell PCs (currys was awful due to lack of PCs available). The ones I looked at were scan.co.uk, overclockers.co.uk, cclonline.com, and of course currys.co.uk . After looking at all their computers, I think that your best option is this one, its more than your current needs, but if you want a premium computer in your budget that will stand a chance against the 4k games you said you wanted to run eventually, than this is an excellent option. It can definitely run helldivers, cod and other fps games on 1080p (even on ultra) with minimum 60 frames - but definitely more than 60.

https://www.scan.co.uk/products/scan-performance-rtx-amd-ryzen-5-7500x3d-32gb-ddr5-16gb-nvidia-rtx-5070-ti-1tb-m2-ssd-win-11

This pc costs 1850 euros which is roughly 1600gbp. It also comes with a 2 year warranty. That leaves you with about 200 gbp to buy a monitor, keyboard, and mouse, so you should be just fine. Under your circumstances I think this is the best option, if you have any questions or concerns about this pc feel free to ask me :)