Just taking the mobo and cpu, the 5600X and b grade x570 Tomahawk is £340
Options you could do.
Below is a more affordable Z690 board, but it does well in reviews and comes with the pcie5 gpu slot, and 4 nvme slots..3 x gen4, 1 x gen3. You could couple that with a 12400F which you can get for £163 for a total of £363(so £23 more). Benefit is the mobo is more future proof, and you'll be able to drop a more powerful cpu in at a later date. It'll support gen13 intel chips that come out next year also. The mobo is new, unopened and not b grade also.
You could get the 12400 cpu which has integrated graphics also for £189 as another option, or the 12600 for £215. From one yt I've seen in gaming, the 12600 isn't that far behind the 12600k, but it lacks the 4 e cores.
Another option is to drop to a B660 motherboard as a more budget option. For budget, looking at hardware unboxed, I'd only recommend the MSI B660M-A Wifi DDR4 board which you can get for £145, coupled with the 12400F for £308.
The 12400F,12400,12500,12600 cpy's aren't available from OCuk for some reason, they just don't stock them. Neither is the MSI B660 mobo above. They have a more premium b660 Tomahawk, but think close enough where going to Z690 chipset then becomes better
From my viewing, the 12400F isn't quite as good as the 5600X, but it is slightly cheaper with B660 mobo if cost is a priority. One thing to remember though is the X570 Tomahawk isn't a budget board, whereas the B660 is a good board, but still budget, and the z690 board more budget, but still a great board (they do a Z690 tomahawk also but that's £250)
My basket at OcUK:
Total: £210.49 (includes delivery: £10.50)
Remember with below they recommended the 12400F due to cost difference, but now with 5600X price reduction, not so simple...it you go to conclusion, it shows charts of performance of the cpu's including the 5600X
Again go to conclusion for quick view, showing the MSI board best budget B660 board