This looks like a good build.

A couple pf considerations; which really come down to your budget and future plans.

The Ryzen 7700 X is a good value per £ spent, and a good chip. But if your budget allows then £140 more gets the Ryzen 9 7950X, which has twice the threads at 16, better specs generally and nearly double the bench marking scores. Obviously prices vary in different regions but I'm seeing the 7700 X at £330 and the 7950X at £470. For 40% more you'd get about 100% more power. Those sorts of things are worth considering when you build - a higher budget now may save you money longer term as you may not need to upgrade for longer and youre already sinking the £330 in which you wouldn't get back when you upgrade.

However you would also need to think about CPU cooling and may end up spending more on a fan too. But fans are generally cheaper and if youre already getting a good fan it'd be moot. Do get a fan; I dont think the 7700 X cones with one and generally stock fansnwith CPUs are OK but not the best for high performance use like gaming.

For graphica the RX 7900 GRE is a slightly better AMD graphics card. Its about 11% more powerful. I'm seeing t at £560 versus £520 for the 7800 XT. About 7% more expensive. 11% is a more marginal boost but again might be worth it. I'd definitely go with AMD at that price range - Nvidia 4070 is similar performance to the 7900 GRE but I'm seeing the 4070 as more expensive and Nvidia drivers are not as good on linux.

Thats not to say the drivers dont work - I do have a 3070 on Linux and I have a good experience gaming. The problems are ive had bad driver updates ive had to roll back, and I have problems with Wayland so use X11.

However if money were not a limit, the top end cards are Nvidia and you'd still get your gaming power from them on linux. Its just frustrating and annoying when drivers lag Windows, or have buggy updates. In terms of value for money and Linux, the AMD RX 7900 GRE is the better buy.

(Edit: worth saying too for single player gaming the ones youre playing are the ones that make good use of ultra high end graphics - so for example Witcher 4 is going to making use of top end graphics in the years ahead. GTA VI too. Not sure that justifies the cost of high end cards though - they are rediculousl overpowered and overpriced fr current uses)

Last thing, again coming down to budget vs future proofing. 32gb of ram is good but maybe worth getting 64gb if you can afford it to future proof. However if sticking with 32gb get a brand and combination you'd hopefully he able to buy more of down the line. Its not a good idea to mix ram sticks so you could get 2 16gb sticks now, and then another two 16gb sticks in the future - so make sure its a decent brand like Corsair that will still sell in 3-5 years. However if you get 64gb you might be OK for 5 and maybe even 10 years.

RAM is also always one of the cheapest and first and easiest ways to boost performance in a systemif you had to pick just 1 item to boost. (Edit: but in your case 32gb is already top end so you probably wouldn't notice the 64gb unless you have some very memory intensive scenarios. I do have 64gb - which I do use for Cities Skylines as I load so many mods. So 64gb can still be a good buy if you'd use it)

Edit 2: also get a 4k gaming monitor because with the specs youre considering you'd be playing at 4k. I play at 4k with high and ultra settings still on my 3070, and that's less powerful than what youre buying.