First off, nothing lasts.
Also, your target price is probably too low.
A 3080Ti for instance is 1100-1200 dollars US (to convert to pounds, multiple by .8...but that's the price here in the US, not sure how prices change in the UK)
So...what's your target time to replace once you get this computer? One year, three, five, seven?
Are you willing to upgrade your video card in the future?
Do you want to spend the money now to make it more of an upgradeable machine, or pay it later?
Anyway, my thoughts for a 5-7 year PC
1) Your motherboard should be PCIe 5.0 or better
2) get a NVMe M.2 Drive. You want at least 4.0, if not a 5.0 drive. Make sure you size it so that you can put everything you want on it.
3) Make sure you have a few other expansion M.2 Drive slots for future drives available on your motherboard
4) next Gen Nvidia cards are coming this year (Rumors are months away), and there is also a big rumor that they will be power hogs. I mean 600 W power hogs.
5) 1200W power supply. Don't cheap out here. Get a good one.
6) Get a good case. With 600W of consumption, that card is going to get HOT. You want good venting to get that air OUT.
7) I still believe in the all-in-one liquid cooling units. Make sure you install it in the proper orientation
8) if you are not playing DVDs on your computer, you don't need a DVD player on your computer.
9) No matter if you go Intel or AMD, get the latest gen CPU. The 12 series is a lot better than the 11 series, but you need windows 11 to run it optimally. You don't need the extreme high end versions, but i7 or i9 or AMD equivalent is good where you should be aiming
10) upgrade your video card after two generations. So the 60 series if you get the 40 series in a few months.
you are probably looking at 4-5k at this point. Not sure how inflation is hitting you over there, so it might be even more. To save money, you can probably drop down to the 3070/4070 series, but the performance from the 3070ti isn't that much better than your current 1080ti
Now the hard part. Unless you are completely in the need for a new machine, wait. The new processors and video cards come out in a few months time. Waiting a few months now gives you another year of future use.